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Full vulnerability report · 2026
CVE-2026-19499High confidence

Buffer overflow in strfmon and strfmon_l right-justification padding

The GNU C Library · glibc

7.7HighCVSS 3.1
Recommended action
Patch only the product branches with a verified fix

High technical severity; prioritise exposed affected systems while verifying vendor guidance. Verified remediation exists for at least one product or source, but 2 structured product or package states remain unresolved. Apply remediation only to the exact product branch confirmed by its source.

Fix availability varies by product
R
Operational reassessment

Published severity in operational context

Open reassessment dashboard →
Published severityHighOperational priority:High, unchanged from published severity.unchanged

Evidence used

  • No CISA KEV confirmation is currently recorded.
  • The selected CVSS metric records a network-reachable, unauthenticated path with no user interaction.
  • EPSS is 0.30% for the current model date.

Compensating controls

  • Validate the affected product branch and deploy the verified fixed release.
  • Restrict the affected network interface to trusted sources where business-safe.
  • Monitor vendor guidance and exploitation sources for a material change.

Verification

  1. Confirm that the asset runs The GNU C Library glibc and falls inside the recorded affected range.
  2. Verify the installed build against the product-specific fixed version after deployment.
  3. Validate exposure, authentication requirements and compensating controls in the actual environment.
  4. Reopen this reassessment when CVSS, KEV, EPSS, exploit evidence or remediation changes.
Mitigation target: Within 30 daysRemediation target: Within 180 days

This automated reassessment organises public evidence. It does not know asset exposure, business impact or control effectiveness and does not replace CVSS or a human risk decision.

Cross-source reconciliation

Remediation availability differs by product scope

Verified remediation exists for at least one product or source, but 2 structured product or package states remain unresolved. Apply remediation only to the exact product branch confirmed by its source.

Distribution package intelligence

Release-specific package status

Debian, ubuntu findings are scoped to the named distribution, release and source package. An absent finding does not mean a package is unaffected.

5 package states
Package result overrides the generic status

BlackTree has verified remediation for at least one product or source, but the relevant distribution still reports no fixed package for 2 affected package states shown here. Treat those rows as affected with no fix until that distribution publishes a fixed version.

Repository candidate not checked

A published vendor fix does not prove that a matching update is enabled and installable on a particular asset. Confirm the local package candidate before scheduling remediation.

Distribution releaseSource packageVendor stateFixed versionEvidence
Debian trixietrixie · sourceglibcAffected, no fix publishedDebian currently tracks this release as open.Not published in this feedDebian Security Tracker ↗Source updated 7 Oct 2026
Debian bookwormbookworm · sourceglibcAffected, no fix publishedDebian currently tracks this release as open.Not published in this feedDebian Security Tracker ↗Source updated 7 Oct 2026
Debian forkyforky · sourceglibcVendor fix publishedDebian records a fixed source-package version for this release.2.43-5Debian Security Tracker ↗Source updated 7 Oct 2026
Debian sidsid · sourceglibcVendor fix publishedDebian records a fixed source-package version for this release.2.43-5Debian Security Tracker ↗Source updated 7 Oct 2026
Ubuntu 24.04 LTSnoble · standard archiveglibcVendor fix publishedCanonical reports that a fixed source package version has been published. Repository candidate availability is not checked by BlackTree.2.39-0ubuntu8.9Canonical Ubuntu Security ↗Source updated 7 Oct 2026
Direct vendor intelligence

Authoritative vendor CSAF and VEX advisories

Structured product status and remediation from the issuing vendor. Product-state explanations are always visible; large lists can be searched or downloaded.

1 current
CVE-2026-19499 · CSAF 2.0 · revision 3 · finalRed Hat Product Securityglibc: Buffer Overflow in strfmon right-justification padding
222 known affected

The vendor explicitly identifies these products as affected by this CVE.

  • glibc as a component of Red Hat Enterprise Linux 10
  • glibc-all-langpacks as a component of Red Hat Enterprise Linux 10
  • glibc-benchtests as a component of Red Hat Enterprise Linux 10
  • glibc-common as a component of Red Hat Enterprise Linux 10
  • glibc-devel as a component of Red Hat Enterprise Linux 10
  • glibc-doc as a component of Red Hat Enterprise Linux 10
  • glibc-gconv-extra as a component of Red Hat Enterprise Linux 10
  • glibc-langpack-aa as a component of Red Hat Enterprise Linux 10
  • glibc-langpack-af as a component of Red Hat Enterprise Linux 10
  • glibc-langpack-agr as a component of Red Hat Enterprise Linux 10
  • glibc-langpack-ak as a component of Red Hat Enterprise Linux 10
  • glibc-langpack-am as a component of Red Hat Enterprise Linux 10
Summary
A flaw was found in glibc. The strfmon and strfmon_l functions are vulnerable to a buffer overflow when processing right-justified width padding. This occurs because an incorrect length is used for an internal memory operation, causing data to be written beyond its intended buffer. An attacker could exploit this by providing specially crafted input, potentially leading to arbitrary code execution or other severe impacts.
Remediation
For details on how to apply this update, which includes the changes described in this advisory, refer to: https://images.redhat.com/
Optional official sources

National CERT insights
?CERT means Computer Emergency Response Team; CSIRT is the closely related term Computer Security Incident Response Team.

Choose official national sources for this report. Each advisory shows its original language. Your selection is remembered on this device and included in shared links.

Official European source

ENISA European Vulnerability Database

Official EUVD identifiers, advisory evidence and known-exploited context. Missing fields are not treated as evidence of low risk.

1 current
ENISA EUVD identifier

EUVD-2026-77675

No EUVD known-exploited evidence

Calling strfmon and strfmon_l in the GNU C Library version 2.38 to 2.44 can write past the end of the caller-supplied output buffer when a conversion uses right-justified width padding. Exploitation requires an application code path that calls strfmon or strfmon_l with right-justified width padding into a destination buffer that is large enough for the padding to succeed but too small for the internal memmove call. The field width or format may be attacker-influenced or a fixed susceptible pattern in the caller. At the time of publication, no network-facing application impact is known.

EUVD state
Present in the current official mapping
Known exploitation
Not present in the current ENISA EUVD known-exploited dataset. This is not proof of no exploitation.
ENISA score
7.7 · CVSS 3.1
Advisory evidence
No linked advisory details stored yet
Recommended actionPatch only the product branches with a verified fix

High technical severity; prioritise exposed affected systems while verifying vendor guidance. Verified remediation exists for at least one product or source, but 2 structured product or package states remain unresolved. Apply remediation only to the exact product branch confirmed by its source.

Fix availability varies by product
01

What, why and how

Calling strfmon and strfmon_l in the GNU C Library version 2.38 to 2.44 can write past the end of the caller-supplied output buffer when a conversion uses right-justified width padding. Exploitation requires an application code path that calls strfmon or strfmon_l with right-justified width padding into a destination buffer that is large enough for the padding to succeed but too small for the internal memmove call. The field width or format may be attacker-influenced or a fixed susceptible pattern in the caller. At the time of publication, no network-facing application impact is known.

What

Calling strfmon and strfmon_l in the GNU C Library version 2.38 to 2.44 can write past the end of the caller-supplied output buffer when a conversion uses right-justified width padding. Exploitation requires an application code path that calls strfmon or strfmon_l with right-justified width padding into a destination buffer that is large enough for the padding to succeed but too small for the internal memmove call. The field width or format may be attacker-influenced or a fixed susceptible pattern in the caller. At the time of publication, no network-facing application impact is known.

Why

A heap overflow condition is a buffer overflow, where the buffer that can be overwritten is allocated in the heap portion of memory, generally meaning that the buffer was allocated using a routine such as malloc().

How

An attacker operating through a network path may attempt exploitation without authentication or user interaction. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.

What

Calling strfmon and strfmon_l in the GNU C Library version 2.38 to 2.44 can write past the end of the caller-supplied output buffer when a conversion uses right-justified width padding. Exploitation requires an application code path that calls strfmon or strfmon_l with right-justified width padding into a destination buffer that is large enough for the padding to succeed but too small for the internal memmove call. The field width or format may be attacker-influenced or a fixed susceptible pattern in the caller. At the time of publication, no network-facing application impact is known.

Why

A heap overflow condition is a buffer overflow, where the buffer that can be overwritten is allocated in the heap portion of memory, generally meaning that the buffer was allocated using a routine such as malloc().

How

An attacker operating through a network path may attempt exploitation without authentication or user interaction. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.

02

Exploit reality and attack path

CVSS severity, EPSS forecast probability, public exploit material and CISA-confirmed exploitation are separate signals.

Observed exploitation
?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.
No confirmed evidence

No CISA KEV match was present at the last successful refresh. This means no confirmation from that source, not proof of no exploitation.

Public PoC / exploit material
?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.
None recorded

No exploit-tagged reference or CISA SSVC proof-of-concept state is currently recorded. Research may still exist outside the structured feeds.

Likely attack path
a network path → Heap-based Buffer Overflow → cause the confidentiality, integrity or availability impact described by the vendor
Attack surface
Network
Privileges required
None: unauthenticated exploitation is possible
User interaction
None
Attack complexity
High: exploitation depends on specific conditions
Security boundary
Unchanged: impact remains within the vulnerable component's security authority
Weakness
?CWE means Common Weakness Enumeration: a standard category for the underlying weakness.
CWE-122 ↗

CWE-122: Heap-based Buffer Overflow. A heap overflow condition is a buffer overflow, where the buffer that can be overwritten is allocated in the heap portion of memory, generally meaning that the buffer was allocated using a routine such as malloc().

CVSS vector
?CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity.
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:L/A:H

Common Vulnerability Scoring System 3.1: the compact vector below is decoded into plain language.

AVNetworkAttack vector: The vulnerable component can be reached over a network.ACHighAttack complexity: Successful exploitation depends on specific conditions outside the attacker's direct control.PRNonePrivileges required: The attacker does not need an account or existing privileges.UINoneUser interaction: No action by another user is required.SUnchangedScope: The security impact remains within the vulnerable component's authority.CHighConfidentiality impact: A successful attack can cause a major loss.ILowIntegrity impact: A successful attack can cause a limited loss.AHighAvailability impact: A successful attack can cause a major loss.
Post-exploitation / living off the land
No specific living-off-the-land technique is confirmed in the structured sources. Monitor normal administration tools for activity inconsistent with the affected service's baseline.
NetworkUnauthenticatedCWE-122
A

Official authority intelligence

Only matched European and national findings are included. Language selectors and unavailable sources are omitted.

ENISA EUVD · EUVD-2026-77675Official EUVD mapping

Calling strfmon and strfmon_l in the GNU C Library version 2.38 to 2.44 can write past the end of the caller-supplied output buffer when a conversion uses right-justified width padding. Exploitation requires an application code path that calls strfmon or strfmon_l with right-justified width padding into a destination buffer that is large enough for the padding to succeed but too small for the internal memmove call. The field width or format may be attacker-influenced or a fixed susceptible pattern in the caller. At the time of publication, no network-facing application impact is known.

Official EUVD record ↗
BSI · German · WID-SEC-2026-3014GNU libc: Mehrere Schwachstellen

Ein Angreifer kann mehrere Schwachstellen in GNU libc ausnutzen, um beliebigen Programmcode auszuführen, vertrauliche Informationen offenzulegen, Daten zu manipulieren, einen Denial-of-Service-Zustand auszulösen oder andere, nicht näher bezeichnete Angriffe durchzuführen.

Official advisory ↗
CSIRT Italia · Italian · vulnerabilita-in-prodotti-gnuVulnerabilità in prodotti GNU

La vulnerabilità identificata tramite la CVE-2026-91752 - di tipo “ Stack-Based Buffer Overflow ” e con score CVSS v4.0 pari a 8.7 - interessa GNU libextractor nelle versioni precedenti alla 1.15 ed è causata da un’inadeguata gestione della memoria nella funzione process_star_office , presente nel componente OLE2 extractor . In particolare, la funzione dimensiona un array a lunghezza variabile nello stack sulla base della dimensione di dati OLE2 controllabili dall’attaccante, consentendo allocazioni fino a circa 4 MB; un utente malevolo potrebbe sfruttare tale vulnerabilità fornendo al sistema target un documento StarOffice/OLE2 opportunamente predisposto al fine di provocare uno stack overflow durante l’estrazione dei metadati, causando il crash dell’applicazione interessata. In particolari scenari applicativi, specialmente in contesti multi-thread, la vulnerabilità potrebbe inoltre consentire l’esecuzione di codice arbitrario remoto sul sistema target.

Official advisory ↗
03

Patch and workaround

Operational remediation based on structured source evidence.

Status
?Patch availability is based on structured fixed-version fields and authoritative update references. If no fix is verified, check the vendor advisory before making a change.
Fix availability varies by product
Affected
Fixed
Action
Use the product-specific evidence above. Patch only products with a verified fixed release, and keep every affected or under-investigation state without a matching fix in the remediation queue.
Workaround
No verified workaround is recorded. If business-safe, reduce exposure to the affected interface and allow only trusted sources until authoritative guidance is available.
04

Evidence and provenance

Published 14 Sept 2026 · Last source change 14 Sept 2026, 19:40 UTC · CWE-122 · Heap-based Buffer Overflow

CVE recordCVE.org · 5.2
CVSS sourceCNA
EPSS source
?The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.
FIRST · tracked since 2026-09-15
European sourceENISA EUVD · EUVD-2026-77675
Product sourceVendor CSAF · Red Hat Product Security
Remediation sourceVendor CSAF · Red Hat Product Security
CWE sourceCNA
NVD statusNVD awaiting enrichment

Core structured fields are present and their contributing authorities are shown above.

Material change intelligence

What changed after publication

View recent updates ↗
  1. Affected versionsThe structured affected or fixed version information changed.
    Before
    glibc as a component of Red Hat Enterprise Linux 10; glibc-all-langpacks as a component of Red Hat Enterprise Linux 10; glibc-benchtests as a component of Red Hat Enterprise Linux 10; glibc-common as a component of Red Hat Enterprise Linux 10; glibc-devel as a component of Red Hat Enterprise Linux 10; glibc-doc as a component of Red Hat Enterprise Linux 10; glibc-gconv-extra as a component of Red Hat Enterprise Linux 10; glibc-langpack-aa as a component of Red Hat Enterprise Linux 10; glibc-langpack-af as a component of Red Hat Enterprise Linux 10; glibc-langpack-agr as a component of Red Hat Enterprise Linux 10; glibc-langpack-ak as a component of Red Hat Enterprise Linux 10; glibc-langpack-am as a component of Red Hat Enterprise Linux 10; glibc-langpack-an as a component of Red Hat Enterprise Linux 10; glibc-langpack-anp as a component of Red Hat Enterprise Linux 10; glibc-langpack-ar as a component of Red Hat Enterprise Linux 10; glibc-langpack-as as a component of Red Hat Enterprise Linux 10; glibc-langpack-ast as a component of Red Hat Enterprise Linux 10; glibc-langpack-ayc as a component of Red Hat Enterprise Linux 10; glibc-langpack-az as a component of Red Hat Enterprise Linux 10; glibc-langpack-be as a component of Red Hat Enterprise Linux 10; glibc-langpack-bem as a component of Red Hat Enterprise Linux 10; glibc-langpack-ber as a component of Red Hat Enterprise Linux 10; glibc-langpack-bg as a component of Red Hat Enterprise Linux 10; glibc-langpack-bhb as a component of Red Hat Enterprise Linux 10; glibc-langpack-bho as a component of Red Hat Enterprise Linux 10; glibc-langpack-bi as a component of Red Hat Enterprise Linux 10; glibc-langpack-bn as a component of Red Hat Enterprise Linux 10; glibc-langpack-bo as a component of Red Hat Enterprise Linux 10; glibc-langpack-br as a component of Red Hat Enterprise Linux 10; glibc-langpack-brx as a component of Red Hat Enterprise Linux 10; and 192 more · Fixed: glibc-main@aarch64 as a component of Red Hat Hardened Images; glibc-main@noarch as a component of Red Hat Hardened Images; glibc-main@src as a component of Red Hat Hardened Images; glibc-main@x86_64 as a component of Red Hat Hardened Images
    After
    glibc as a component of Red Hat Enterprise Linux 10; glibc-all-langpacks as a component of Red Hat Enterprise Linux 10; glibc-benchtests as a component of Red Hat Enterprise Linux 10; glibc-common as a component of Red Hat Enterprise Linux 10; glibc-devel as a component of Red Hat Enterprise Linux 10; glibc-doc as a component of Red Hat Enterprise Linux 10; glibc-gconv-extra as a component of Red Hat Enterprise Linux 10; glibc-langpack-aa as a component of Red Hat Enterprise Linux 10; glibc-langpack-af as a component of Red Hat Enterprise Linux 10; glibc-langpack-agr as a component of Red Hat Enterprise Linux 10; glibc-langpack-ak as a component of Red Hat Enterprise Linux 10; glibc-langpack-am as a component of Red Hat Enterprise Linux 10; glibc-langpack-an as a component of Red Hat Enterprise Linux 10; glibc-langpack-anp as a component of Red Hat Enterprise Linux 10; glibc-langpack-ar as a component of Red Hat Enterprise Linux 10; glibc-langpack-as as a component of Red Hat Enterprise Linux 10; glibc-langpack-ast as a component of Red Hat Enterprise Linux 10; glibc-langpack-ayc as a component of Red Hat Enterprise Linux 10; glibc-langpack-az as a component of Red Hat Enterprise Linux 10; glibc-langpack-be as a component of Red Hat Enterprise Linux 10; glibc-langpack-bem as a component of Red Hat Enterprise Linux 10; glibc-langpack-ber as a component of Red Hat Enterprise Linux 10; glibc-langpack-bg as a component of Red Hat Enterprise Linux 10; glibc-langpack-bhb as a component of Red Hat Enterprise Linux 10; glibc-langpack-bho as a component of Red Hat Enterprise Linux 10; glibc-langpack-bi as a component of Red Hat Enterprise Linux 10; glibc-langpack-bn as a component of Red Hat Enterprise Linux 10; glibc-langpack-bo as a component of Red Hat Enterprise Linux 10; glibc-langpack-br as a component of Red Hat Enterprise Linux 10; glibc-langpack-brx as a component of Red Hat Enterprise Linux 10; and 192 more · Fixed: compat-libpthread-nonshared-0:2.43-8.3.hum1@aarch64 as a component of Red Hat Hardened Images; compat-libpthread-nonshared-0:2.43-8.3.hum1@x86_64 as a component of Red Hat Hardened Images; glibc-0:2.43-8.3.hum1@src as a component of Red Hat Hardened Images; glibc-doc-0:2.43-8.3.hum1@noarch as a component of Red Hat Hardened Images
    Red Hat Product Security ↗
  2. ENISA EUVD mappingEUVD-2026-77675 was added to the official ENISA EUVD mapping for this CVE.
    Before
    not recorded
    After
    {"euvdId":"EUVD-2026-77675"}
    ENISA EUVD ↗
  3. Affected versionsThe structured affected or fixed version information changed.
    Before
    glibc: 2.38 ≤ 2.44 · Fixed: No fixed version is explicitly recorded in the structured CVE data.
    After
    glibc: 2.38 ≤ 2.44 · Fixed: For details on how to apply this update, which includes the changes described in this advisory, refer to: https://images.redhat.com/
    Red Hat Product Security ↗
  4. Remediation statusRemediation status changed from Awaiting fix to Patch available.
    Before
    Awaiting fix
    After
    Patch available
    Red Hat Product Security ↗
  5. Catalogue recordCVE added to the BlackTree catalogue.
    CNA ↗
Material fields only · duplicate refreshes suppressed · history retained for the configured operational retention period
CVE published
Fixed release recorded from official guidance
Fixed release recorded from official guidance
ENISA EUVD · EUVD-2026-77675↗Red Hat Product Security security advisory↗CVE authority or vendor reference↗Official CVE record (CNA and ADP data)↗NVD record↗
Technical terms and abbreviations used in this report
CVE
Common Vulnerabilities and Exposures: the public identifier for one disclosed vulnerability.
CVSS
Common Vulnerability Scoring System: a technical severity framework; it is not patching priority by itself.
EPSS
Exploit Prediction Scoring System: FIRST's estimate of the probability that exploitation activity will be observed in the next 30 days; it is a forecast, not confirmation.
CWE
Common Weakness Enumeration: the standard category describing the underlying software or hardware weakness.
CNA
CVE Numbering Authority: an organisation authorised to assign and publish CVE records.
CISA ADP
Cybersecurity and Infrastructure Security Agency Authorized Data Publisher: structured enrichment added to a CVE record.
NVD
National Vulnerability Database: NIST's enrichment service for CVE records.
CERT / CSIRT
A computer security incident response team that publishes warnings or coordinates incident response.
PoC
Proof of concept: public material that demonstrates or helps reproduce exploitation.
CSAF
Common Security Advisory Framework: a machine-readable format for security advisories.
LoTL
Living off the land: abuse of legitimate tools or system functions during an attack.
Free version - for non-commercial use only.CVE-2026-19499 · cve.blacktree.nl