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Advisory record · GHSA-mm57-4v3p-rchx

pyasn1 has quadratic-complexity denial of service in binary REAL decoding

CVSS 7.5 HighEPSS 0.0043 · 36th percentile

Published by the GitHub Advisory Database at 30 Oct 2026, 23:06 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

PackageEcosystemAffectedFixed in
pyasn1PyPI<0.6.50.6.5
Identifiers
GHSA-mm57-4v3p-rchx · CVE-2026-119197
Weakness (CWE)
CWE-407
Tags
Published
30 Oct 2026
Updated
30 Oct 2026

Machine-written summary

Summary written by Claude Haiku from the source advisory. Not reviewed by a person.

pyasn1 versions below 0.6.5 (including 0.6.4 and earlier) are vulnerable to quadratic-complexity CPU consumption when decoding binary-encoded ASN.1 REAL values with large mantissas through the BER, CER, or DER decoders. An attacker who can supply ASN.1 data that an application passes to these decoders can tie up a CPU core for seconds or longer during decode(), with no need to use the resulting value. The fix is in pyasn1 0.6.5, so upgrade to that version; until then, the source suggests rejecting or strictly size-limiting untrusted input that may contain REAL values.

Written 31 Oct 2026.

Not analysed yet

We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.

Severity and exploitation

ScoreRatingCVSSVectorSource
7.5 High 3.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H CNA (GitHub_M)
  • CISA KEV Not listed.
  • EPSS 0.0043, the 36th percentile, on 5 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

Timeline

  1. 31 Oct 2026, 14:07 UTC First seen by agentprime
  2. 31 Oct 2026, 14:07 UTC Confirmed by OSV

Sources

Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code.