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Full vulnerability report · 2026
CVE-2026-40467High confidence

Use after free in gawk

GNU · gawk

5.1MediumCVSS 4.0
Recommended action
Scheduled

Medium technical severity with no CISA KEV confirmation; remediate through the normal risk-based patch cycle unless local exposure raises the priority.

Patch available
Distribution package intelligence

Ubuntu vendor package status

Canonical’s release and source-package findings are shown separately from local repository availability.

1 package state
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.

Ubuntu releaseSource packageVendor stateFixed versionEvidence
Ubuntu 24.04 LTSnoble · standard archivegawkVendor fix publishedCanonical reports that a fixed source package version has been published. Repository candidate availability is not checked by BlackTree.1:5.2.1-2ubuntu0.1Canonical record ↗Source updated 10 Sept 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-2026-40467 · CSAF 2.0 · revision 3 · finalRed Hat Product Securitygawk: gawk: Denial of Service due to Use After Free vulnerability in io.c
9 known affected

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

  • gawk-all-langpacks as a component of Red Hat Enterprise Linux 10
  • gawk.src as a component of Red Hat Enterprise Linux 10
  • gawk.src as a component of Red Hat Enterprise Linux 6
  • gawk.src as a component of Red Hat Enterprise Linux 7
  • gawk.src as a component of Red Hat Enterprise Linux 8
  • gawk-all-langpacks as a component of Red Hat Enterprise Linux 9
  • gawk.src as a component of Red Hat Enterprise Linux 9
  • openshift/ose-rhel-coreos-8 as a component of Red Hat OpenShift Container Platform 4
  • openshift/ose-rhel-coreos-9 as a component of Red Hat OpenShift Container Platform 4
Summary
A flaw was found in gawk. A Use After Free vulnerability exists in the do_getline_redir() routine within the io.c program file. This vulnerability can be triggered by an attacker, potentially leading to a system crash and causing a Denial of Service (DoS).
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.

Select the national-authority views to include. The exact source language is shown on each matched advisory. Your choice is remembered on this device and encoded in the shareable URL.

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-2026-43492

No EUVD known-exploited evidence

ENISA has published the identifier mapping but no EUVD description has been stored yet.

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
Not supplied in the stored EUVD record
Advisory evidence
No linked advisory details stored yet
Recommended actionScheduled

Medium technical severity with no CISA KEV confirmation; remediate through the normal risk-based patch cycle unless local exposure raises the priority.

Patch available
01

What, why and how

Use After Free vulnerability has been found in "io.c" program file of gawk (do_getline_redir() routine). This issue may lead to a crash. It affects gawk in versions 5.4.0 and below.

What

Use After Free vulnerability has been found in "io.c" program file of gawk (do_getline_redir() routine). This issue may lead to a crash. It affects gawk in versions 5.4.0 and below.

Why

The program can continue using memory after it has been released, producing unsafe and attacker-influenceable behaviour.

How

An attacker operating through local access may attempt exploitation without authentication or user interaction. If successful, the issue may disrupt the affected service.

What

Use After Free vulnerability has been found in "io.c" program file of gawk (do_getline_redir() routine). This issue may lead to a crash. It affects gawk in versions 5.4.0 and below.

Why

The program can continue using memory after it has been released, producing unsafe and attacker-influenceable behaviour.

How

An attacker operating through local access may attempt exploitation without authentication or user interaction. If successful, the issue may disrupt the affected service.

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
local access → Use After Free → disrupt the affected service
Attack surface
Local
Privileges required
None: unauthenticated exploitation is possible
User interaction
None
Attack complexity
Low: no specialised conditions are recorded
Security boundary
Not a CVSS 4.0 base metric
Weakness
?CWE means Common Weakness Enumeration: a standard category for the underlying weakness.
CWE-416 ↗

CWE-416: Use After Free. The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory belongs to the code that operates on the new pointer.

CVSS vector
?CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity.
CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N

Common Vulnerability Scoring System 4.0: the compact vector below is decoded into plain language.

AVLocalAttack vector: The attacker needs local access to the vulnerable system.ACLowAttack complexity: No specialised conditions are required beyond attacker-controlled input.ATNoneAttack requirements: No additional deployment or execution condition is required.PRNonePrivileges required: The attacker does not need an account or existing privileges.UINoneUser interaction: No action by another user is required.VCNoneVulnerable-system confidentiality: No direct loss is represented by this metric.VINoneVulnerable-system integrity: No direct loss is represented by this metric.VALowVulnerable-system availability: A successful attack can cause a limited loss.SCNoneSubsequent-system confidentiality: No direct loss is represented by this metric.SINoneSubsequent-system integrity: No direct loss is represented by this metric.SANoneSubsequent-system availability: No direct loss is represented by this metric.
Post-exploitation / living off the land
The issue can support a local privilege or sandbox boundary transition; normal system utilities may then be available in the gained context.
UnauthenticatedDenial of serviceCWE-416
A

Official authority intelligence

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

CERT Polska · Polish · CVE-2026-40467CERT Polska w social mediach

CERT Polska otrzymał zgłoszenie o podatnościach w oprogramowaniu GNU gawk i koordynował proces ujawniania informacji. Podatność CVE-2026-40467 : W pliku źródłowym io.c programu gawk (procedura do_getline_redir() ) wykryto podatność typu Use After Free. Może ona prowadzić do awarii programu. Podatność CVE-2026-40468 : W pliku źródłowym builtin.c programu gawk wykryto podatność typu integer overflow. Może ona prowadzić do wyczerpania pamięci systemu operacyjnego oraz zostać wykorzystana do nadpisania metadanych sterty i obiektów bajtami kontrolowanymi przez atakującego. Podatność CVE-2026-40469 : W pliku źródłowym builtin.c programu gawk (procedura do_sub() ) wykryto podatność typu integer overflow. Może ona zostać wykorzystana do nadpisania metadanych sterty i obiektów, powodując awarię programu. Podatność dotyczy 32-bitowych kompilacji programu gawk. Podatność CVE-2026-40553 : W pliku źródłowym extension/readdir.c programu gawk (procedura ftype() ) wykryto podatność typu buffer overflow. Może ona zostać wykorzystana do spowodowania awarii programu, a potencjalnie również do wykonania kodu, choć możliwość ta nie została potwierdzona. Podatności zostały wyeliminowane w wydaniu 5.4.1 programu gawk.

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.
Patch available
Affected
gawk-all-langpacks as a component of Red Hat Enterprise Linux 10; gawk.src as a component of Red Hat Enterprise Linux 10; gawk.src as a component of Red Hat Enterprise Linux 6; gawk.src as a component of Red Hat Enterprise Linux 7; gawk.src as a component of Red Hat Enterprise Linux 8; gawk-all-langpacks as a component of Red Hat Enterprise Linux 9; gawk.src as a component of Red Hat Enterprise Linux 9; openshift/ose-rhel-coreos-8 as a component of Red Hat OpenShift Container Platform 4; openshift/ose-rhel-coreos-9 as a component of Red Hat OpenShift Container Platform 4
Fixed
gawk-main@aarch64 as a component of Red Hat Hardened Images; gawk-main@noarch as a component of Red Hat Hardened Images; gawk-main@src as a component of Red Hat Hardened Images; gawk-main@x86_64 as a component of Red Hat Hardened Images
Action
For details on how to apply this update, which includes the changes described in this advisory, refer to: https://images.redhat.com/
Workaround
No verified workaround is recorded. Limit untrusted access and use least privilege until authoritative guidance is available.
04

Evidence and provenance

Published 13 Jul 2026 · Last source change 13 Jul 2026, 13:02 UTC · CWE-416 · Use After Free

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 2026-08-14
European sourceENISA EUVD · EUVD-2026-43492
Product sourceVendor CSAF · Red Hat Product Security
Remediation sourceVendor CSAF · Red Hat Product Security
CWE sourceCNA
NVD statusNVD enriched

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
    gawk-all-langpacks as a component of Red Hat Enterprise Linux 10; gawk.src as a component of Red Hat Enterprise Linux 10; gawk.src as a component of Red Hat Enterprise Linux 6; gawk.src as a component of Red Hat Enterprise Linux 7; gawk.src as a component of Red Hat Enterprise Linux 8; gawk-all-langpacks as a component of Red Hat Enterprise Linux 9; gawk.src as a component of Red Hat Enterprise Linux 9; openshift/ose-rhel-coreos-9 as a component of Red Hat OpenShift Container Platform 4 · Fixed: gawk-main@aarch64 as a component of Red Hat Hardened Images; gawk-main@noarch as a component of Red Hat Hardened Images; gawk-main@src as a component of Red Hat Hardened Images; gawk-main@x86_64 as a component of Red Hat Hardened Images
    After
    gawk-all-langpacks as a component of Red Hat Enterprise Linux 10; gawk.src as a component of Red Hat Enterprise Linux 10; gawk.src as a component of Red Hat Enterprise Linux 6; gawk.src as a component of Red Hat Enterprise Linux 7; gawk.src as a component of Red Hat Enterprise Linux 8; gawk-all-langpacks as a component of Red Hat Enterprise Linux 9; gawk.src as a component of Red Hat Enterprise Linux 9; openshift/ose-rhel-coreos-8 as a component of Red Hat OpenShift Container Platform 4; openshift/ose-rhel-coreos-9 as a component of Red Hat OpenShift Container Platform 4 · Fixed: gawk-main@aarch64 as a component of Red Hat Hardened Images; gawk-main@noarch as a component of Red Hat Hardened Images; gawk-main@src as a component of Red Hat Hardened Images; gawk-main@x86_64 as a component of Red Hat Hardened Images
    Red Hat Product Security ↗
Material fields only · duplicate refreshes suppressed · history retained for the configured operational retention period
CVE published
Fixed release or patch reference recorded
ENISA EUVD · EUVD-2026-43492↗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-2026-40467 · cve.blacktree.nl