BlackTreeCVE Intelligence
← Back to the CVE catalogue
Full vulnerability report · 2026
CVE-2026-58081High confidence

Heap based buffer overflow in iconv(3)

FreeBSD · FreeBSD

9.8CriticalCVSS 3.1
Recommended action
Within 72 hours

Critical technical impact with a remotely reachable, unauthenticated path; no CISA KEV confirmation is currently recorded.

Fix not verified
R
Operational reassessment

Published severity in operational context

Open reassessment dashboard →
Published severityCriticalOperational priority:Critical, 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 0.52% for the current model date.

Compensating controls

  • 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 FreeBSD FreeBSD and falls inside the recorded affected range.
  2. Recheck the vendor advisory before scheduling a change because no verified fixed version is currently retained.
  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 3 daysRemediation target: Within 90 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.

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-2026-58081 · CSAF 2.0 · revision 3 · finalRed Hat Product Securityiconv-freebsd: iconv: Heap-based buffer overflow in encoding modules
26 known not affected

The vendor explicitly states that these products are not affected by this CVE.

  • php as a component of Red Hat Enterprise Linux 9
  • php-bcmath as a component of Red Hat Enterprise Linux 9
  • php-cli as a component of Red Hat Enterprise Linux 9
  • php-common as a component of Red Hat Enterprise Linux 9
  • php-dba as a component of Red Hat Enterprise Linux 9
  • php-dbg as a component of Red Hat Enterprise Linux 9
  • php-devel as a component of Red Hat Enterprise Linux 9
  • php-embedded as a component of Red Hat Enterprise Linux 9
  • php-enchant as a component of Red Hat Enterprise Linux 9
  • php-ffi as a component of Red Hat Enterprise Linux 9
  • php-fpm as a component of Red Hat Enterprise Linux 9
  • php-gd as a component of Red Hat Enterprise Linux 9
Summary
A flaw was found in iconv. Several encoding modules, including HZ, UTF-7, VIQR, and ZW, did not properly validate the size of the provided output buffer before writing converted characters. This oversight could allow an application using iconv to convert untrusted input with one of the affected encodings to experience buffer overflows, potentially leading to denial of service or arbitrary code execution.
Remediation
No remediation text is recorded.
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-2026-62348

No EUVD known-exploited evidence

Several encoding modules, including HZ, UTF-7, VIQR, and ZW, did not properly check the size of the caller-supplied output buffer before writing converted characters. An application that uses iconv(3) to convert untrusted input to or from one of the affected encodings may be vulnerable to buffer overflows if it uses one of the affected encoding modules.

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
9.8 · CVSS 3.1
Advisory evidence
No linked advisory details stored yet
Recommended actionWithin 72 hours

Critical technical impact with a remotely reachable, unauthenticated path; no CISA KEV confirmation is currently recorded.

Fix not verified
01

What, why and how

Several encoding modules, including HZ, UTF-7, VIQR, and ZW, did not properly check the size of the caller-supplied output buffer before writing converted characters. An application that uses iconv(3) to convert untrusted input to or from one of the affected encodings may be vulnerable to buffer overflows if it uses one of the affected encoding modules.

What

Several encoding modules, including HZ, UTF-7, VIQR, and ZW, did not properly check the size of the caller-supplied output buffer before writing converted characters. An application that uses iconv(3) to convert untrusted input to or from one of the affected encodings may be vulnerable to buffer overflows if it uses one of the affected encoding modules.

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

Several encoding modules, including HZ, UTF-7, VIQR, and ZW, did not properly check the size of the caller-supplied output buffer before writing converted characters. An application that uses iconv(3) to convert untrusted input to or from one of the affected encodings may be vulnerable to buffer overflows if it uses one of the affected encoding modules.

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
Low: no specialised conditions are recorded
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:L/PR:N/UI:N/S:U/C:H/I:H/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.ACLowAttack complexity: No specialised conditions are required beyond attacker-controlled input.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.IHighIntegrity impact: A successful attack can cause a major 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-2026-62348Official EUVD mapping

Several encoding modules, including HZ, UTF-7, VIQR, and ZW, did not properly check the size of the caller-supplied output buffer before writing converted characters. An application that uses iconv(3) to convert untrusted input to or from one of the affected encodings may be vulnerable to buffer overflows if it uses one of the affected encoding modules.

Official EUVD record ↗
BSI · German · WID-SEC-2026-2165FreeBSD Project FreeBSD OS: Mehrere Schwachstellen

Ein Angreifer kann mehrere Schwachstellen in FreeBSD Project FreeBSD OS ausnutzen, um seine Privilegien zu erhöhen, um Informationen offenzulegen, um Dateien zu manipulieren, um einen Denial of Service Angriff durchzuführen, und um beliebigen Programmcode auszuführen.

Official advisory ↗
Cyber Security Agency of Singapore · English · CSA-SB-20260826Security Bulletin 26 Aug 2026

The Cyber Security Agency of Singapore included this CVE in its official Security Bulletin 26 Aug 2026, published on 26 August 2026. Open the linked bulletin for the product, severity and reference information published in that issue.

Official advisory ↗
JVN iPedia · Japanese · JVNDB-2026-031054FreeBSDにおけるヒープベースのバッファオーバーフローの脆弱性

HZ、UTF-7、VIQR、ZWを含むいくつかのエンコーディングモジュールは、変換された文字を書き込む前に、呼び出し元から提供された出力バッファのサイズを適切にチェックしていませんでした。iconv(3)を使用して信頼できない入力を影響を受けるエンコーディングのいずれかに変換するアプリケーションは、これらのエンコーディングモジュールを使用する場合、バッファオーバーフローの脆弱性が発生する可能性があります。

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 not verified
Affected
FreeBSD: 15.1-RELEASE < p1, 15.0-RELEASE < p11, 14.4-RELEASE < p7, 14.3-RELEASE < p16
Fixed
No fixed version is explicitly recorded in the structured CVE data.
Action
No verified patch reference is present in the current structured sources. Check the vendor advisory before making a change.
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 19 Aug 2026 · Last source change 26 Aug 2026, 17:56 UTC · CWE-122 · Heap-based Buffer Overflow

CVE recordCVE.org · 5.2
CVSS sourceCISA ADP
EPSS source
?The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.
FIRST · tracked since 2026-08-23
European sourceENISA EUVD · EUVD-2026-62348
Product sourceCNA
Remediation sourceCVE/CNA references
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. Vendor guidanceAuthoritative vendor guidance changed from remediation: access.redhat.com/CVE-2026-58081 to remediation: access.redhat.com/CVE-2026-58081.
    Before
    remediation: access.redhat.com/CVE-2026-58081
    After
    remediation: access.redhat.com/CVE-2026-58081
    Red Hat Product Security ↗
  2. Remediation statusRemediation status changed from Mitigation available to Awaiting fix.
    Before
    Mitigation available
    After
    Awaiting fix
    Red Hat Product Security ↗
  3. Affected versionsThe structured affected or fixed version information changed.
    Before
    php as a component of Red Hat Enterprise Linux 9; php-bcmath as a component of Red Hat Enterprise Linux 9; php-cli as a component of Red Hat Enterprise Linux 9; php-common as a component of Red Hat Enterprise Linux 9; php-dba as a component of Red Hat Enterprise Linux 9; php-dbg as a component of Red Hat Enterprise Linux 9; php-devel as a component of Red Hat Enterprise Linux 9; php-embedded as a component of Red Hat Enterprise Linux 9; php-enchant as a component of Red Hat Enterprise Linux 9; php-ffi as a component of Red Hat Enterprise Linux 9; php-fpm as a component of Red Hat Enterprise Linux 9; php-gd as a component of Red Hat Enterprise Linux 9; php-gmp as a component of Red Hat Enterprise Linux 9; php-intl as a component of Red Hat Enterprise Linux 9; php-ldap as a component of Red Hat Enterprise Linux 9; php-mbstring as a component of Red Hat Enterprise Linux 9; php-mysqlnd as a component of Red Hat Enterprise Linux 9; php-odbc as a component of Red Hat Enterprise Linux 9; php-opcache as a component of Red Hat Enterprise Linux 9; php-pdo as a component of Red Hat Enterprise Linux 9; php-pgsql as a component of Red Hat Enterprise Linux 9; php-process as a component of Red Hat Enterprise Linux 9; php-snmp as a component of Red Hat Enterprise Linux 9; php-soap as a component of Red Hat Enterprise Linux 9; php-xml as a component of Red Hat Enterprise Linux 9; php.src as a component of Red Hat Enterprise Linux 9
    After
    Red Hat Product Security ↗
  4. SeveritySeverity changed from Unknown to Critical.
    Before
    Unknown
    After
    Critical
    CISA ADP ↗
  5. CVSS scoreCVSS score changed from not recorded to 9.8 (CVSS 3.1 · CISA ADP · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H).
    Before
    not recorded
    After
    9.8 (CVSS 3.1 · CISA ADP · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H)
    CISA ADP ↗
  6. Catalogue recordCVE added to the BlackTree catalogue.
    CNA ↗
Material fields only · duplicate refreshes suppressed · history retained for the configured operational retention period
CVE published
ENISA EUVD · EUVD-2026-62348↗Vendor CSAF · Red Hat Product Security↗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-2026-58081 · cve.blacktree.nl