# CVE-2026-125709: Libstdc++: overflow leaves streambuf in inconsistent state on i/o error.

Status: published. Published: 2026-11-10. Updated: 2026-11-14.

A flaw was found in libstdc++. When a byte-by-byte write operation fails during file stream processing, the library may still append data into the internal memory buffer. An attacker capable of inducing repeated write failures in an affected service can trigger a buffer overflow, potentially resulting in a Denial of Service (DoS) or memory corruption.

## Remediation

No remediation reported in collected sources

## Affected products and versions

- Red Hat / Red Hat Hardened Images (gcc-main): ≥ 16.2.1-3.3.hum1; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 10 (gcc): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 10 (gcc-toolset-15-gcc): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 10 (gcc-toolset-16-gcc): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 10 (mingw-gcc): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 6 (compat-gcc-295): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 6 (compat-gcc-296): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 6 (compat-gcc-32): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 6 (compat-gcc-34): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 6 (gcc): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 7 (compat-gcc-32): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 7 (compat-gcc-34): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 7 (compat-gcc-44): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 7 (gcc): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 8 (gcc): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 8 (gcc-toolset-15-gcc): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 8 (mingw-gcc): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 9 (gcc): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 9 (gcc-toolset-15-gcc): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 9 (gcc-toolset-16-gcc): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 9 (mingw-gcc): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat Hardened Images (gcc13): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat OpenShift Container Platform 4 (openshift/ose-rhel-coreos-8): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat OpenShift Container Platform 4 (openshift/ose-rhel-coreos-9): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat OpenShift Container Platform 5 (openshift/ose-rhel-coreos-9): Version range not reported. Source: CNA: redhat

## Severity and prioritization

- CVSS 3.1: 4.2 (medium); CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:L/A:L; source: CNA: redhat

- CVSS 3.1: 4.2 (medium); CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:L/A:L; source: NVD: secalert@redhat.com

- CISA KEV: No listing in collected sources

- EPSS: 0.20% as of 2026-11-13; percentile 10.52%

- SSVC: exploitation none; automatable no; technical impact partial; source ADP: CISA-ADP

- Weaknesses: CWE-787

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://access.redhat.com/errata/RHSA-2026:100125 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/security/cve/CVE-2026-125709 (CNA: redhat; vdb-entry, x_refsource_REDHAT)

- https://bugzilla.redhat.com/show_bug.cgi?id=2569390 (CNA: redhat; issue-tracking, x_refsource_REDHAT)

- https://access.redhat.com/security/cve/CVE-2026-125709 (secalert@redhat.com)

- https://bugzilla.redhat.com/show_bug.cgi?id=2569390 (secalert@redhat.com)

## Provenance

- CNA: redhat: https://www.cve.org/CVERecord?id=CVE-2026-125709; retrieved 2026-11-14; source updated 2026-11-14

- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-125709; retrieved 2026-11-11; source updated 2026-11-10

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2026-125709; retrieved 2026-11-14; source updated Not reported

Revision: fb36dee78a44febe5de26ba5ac28871e9e410bc5304785768b317e6e7d9223d3

Canonical: https://y2.dev/cve/CVE-2026-125709

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