Quick answers
- Is CVE-2026-125709 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-125709 being exploited in the wild.
- How severe is CVE-2026-125709?
- Medium severity, with a CVSS score of 4.2, published 10 November 2026.
- Which products and versions are affected?
- GNU libstdc++.
- Is there a fix for CVE-2026-125709?
- No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
- How is CVE-2026-125709 attacked?
- It is attacked over the network, in a software library.
- Am I affected by CVE-2026-125709?
- Check whether you run Gnu Libstdc++. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.
Technical details
A byte-by-byte write failure in file stream processing leaves libstdc++'s streambuf in an inconsistent state, allowing subsequent data to be appended beyond buffer bounds (CWE-787). The vulnerability requires an attacker to induce repeated filesystem write errors on a service implementing vulnerable single-character output routines during failure conditions. Exploitation is limited to custom or network-exposed applications; standard stream output and default system utilities are not affected.
Affected products
- GNU libstdc++
Timeline
- 2026-11-10: disclosed