Affects widely-used Python stdlib; potential RCE/crash across apps, high impact.
CVE-2026-6100
Use-after-free in Python stdlib decompressors when reusing after MemoryError.
Is CVE-2026-6100 being exploited?
Not confirmed. CVE-2026-6100 does not appear in CISA's Known Exploited Vulnerabilities catalog, which records only exploitation that has been observed and reported publicly. That is evidence of absence of a report, not evidence the flaw is unattacked. EPSS currently estimates a 0.58% probability of exploitation in the next 30 days.
How severe is CVE-2026-6100?
CVE-2026-6100 is rated Critical with a CVSS score of 9.1. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.
Is there a patch for CVE-2026-6100?
Yes. A fix has been recorded for CVE-2026-6100. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-6100 affect?
CVE-2026-6100 affects Python standard library (lzma, bz2, gzip). Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-6100?
Update Python to patched release; avoid reusing decompressor after errors
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Possible remote code execution or crash by memory corruption if a decompressor is reused after a MemoryError.
Patch when possible
- affected< 3.10.21
- affected>= 3.11.0 and < 3.11.16
- affected>= 3.12.0 and < 3.12.14
- affected>= 3.13.0 and < 3.13.14
- affected>= 3.14.0a1 and < 3.14.5rc1
- affected>= 3.15.0a1 and < 3.15.0b1
As published in the CVE Program record. A version outside these ranges is not a statement that it is unaffected — vendors sometimes understate a range, and distribution-backported builds carry upstream numbers that do not reflect what was patched into them.