CVE-2026-59884: Parsedmarc · pyasn1 BER/CER/DER decoder denial of service via unbounded long-form tag IDs
Affects parsedmarcSource GCVE Database
Not known to be exploited · CVSS 7.5 High : upgrade to 10.2.1 soon.
Data as of 1 Nov 2026, 00:23 UTC
- Patch
- Available – fixed in 10.2.1
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:HExploitation evidence
Disclosed: evidence found.
CVE published 13 Aug 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 31 Oct 2026.
What to do
Upgrade parsedmarc to 10.2.1.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
Homebrewparsedmarcpkg:brew/parsedmarcOther threats | Affected
| Fixed in
|
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
AI-suggested
A patch is available in parsedmarc version 10.2.1 (pyasn1 0.6.4) which limits long-form tag IDs to 20 octets and improves error handling. Users should upgrade to this fixed version. As a workaround, applications can bound the size of untrusted input passed to the decode() function to prevent excessive resource consumption. No other mitigations are specified.
Description
A denial of service vulnerability exists in the pyasn1 BER/CER/DER decoder used by parsedmarc, caused by unbounded long-form tag IDs. The decoder accumulates continuation octets without an upper limit, allowing crafted inputs to cause excessive CPU consumption. On Python 3.11 and later, this can also trigger unhandled ValueError exceptions during error message formatting, potentially bypassing error handling. The issue affects decoding of untrusted BER/CER/DER inputs and was fixed in version 10.2.1 by limiting tag ID length and improving error handling.
References
- github.com/pyasn1/pyasn1/security/advisories/GHSA-m4p7-r5rc-7g4j (opens in a new tab)
- nvd.nist.gov/vuln/detail/CVE-2026-59884 (opens in a new tab)
- github.com/pyasn1/pyasn1/commit/628e36ecbb5277a3f01572ce418ef54271b165a5 (opens in a new tab)
- github.com/pyasn1/pyasn1 (opens in a new tab)
- github.com/pyasn1/pyasn1/releases/tag/v0.6.4 (opens in a new tab)
- github.com/pypa/advisory-database/tree/main/vulns/pyasn1/PYSEC-2026-3455.yaml (opens in a new tab)