# CVE-2026-121997: Gdb: gdbserver: heap buffer overflow in cmd_qtdpsrc via qtdpsrc declared/actual length mismatch

Status: published. Published: 2026-11-05. Updated: 2026-11-06.

A heap buffer overflow in gdbserver's QTDPsrc packet handler allows an unauthenticated remote attacker to achieve native code execution in the gdbserver process. The vulnerability results from a mismatch between a packet's declared source length and the actual data length, causing hex2bin to write beyond the allocated heap buffer.

## Remediation

- workaround: There is no mitigation for this vulnerability. gdbserver has no authentication mechanism; exposure is limited only by network access to the gdbserver port. (source: CNA: redhat)

## Affected products and versions

- Red Hat / Red Hat Enterprise Linux 10 (crash): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 10 (gdb): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 6 (gdb): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 7 (gdb): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 8 (crash): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 8 (gcc-toolset-14-gdb): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 8 (gcc-toolset-15-gdb): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 8 (gdb): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 9 (crash): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 9 (gdb): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat Hardened Images (gdb): Version range not reported. Source: CNA: redhat

## Severity and prioritization

- CVSS 3.1: 8.1 (high); CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H; source: CNA: redhat

- CVSS 3.1: 8.1 (high); CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H; source: NVD: secalert@redhat.com

- CISA KEV: No listing in collected sources

- EPSS: Not available

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

- Weaknesses: CWE-122

## Exploit evidence

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

## References

- https://access.redhat.com/security/cve/CVE-2026-121997 (CNA: redhat; vdb-entry, x_refsource_REDHAT)

- https://bugzilla.redhat.com/show_bug.cgi?id=2565679 (CNA: redhat; issue-tracking, x_refsource_REDHAT)

- https://access.redhat.com/security/cve/CVE-2026-121997 (secalert@redhat.com)

- https://bugzilla.redhat.com/show_bug.cgi?id=2565679 (secalert@redhat.com)

## Provenance

- CNA: redhat: https://www.cve.org/CVERecord?id=CVE-2026-121997; retrieved 2026-11-06; source updated 2026-11-06

- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-121997; retrieved 2026-11-06; source updated 2026-11-06

Revision: 47430b1095526892e4b20416a569d92017588cc1168cef15a4ffb177f0582fbb

Canonical: https://y2.dev/cve/CVE-2026-121997

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