CVE-2026-59884: Molecule · pyasn1 BER/CER/DER decoder denial of service via unbounded long-form tag IDs
Affects moleculeSource GCVE Database
Not known to be exploited · CVSS 7.5 High : upgrade to 26.6.0_1 or 3.0.5 soon.
Data as of 1 Nov 2026, 01:50 UTC
- Patch
- Available – fixed in 26.6.0_1, 3.0.5
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 molecule to 26.6.0_1 or 3.0.5.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
Homebrewmoleculepkg:brew/moleculeOther 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 pyasn1 versions 3.0.5 and 26.6.0_1 that limits long-form tag IDs to 20 octets and improves error handling. Users should upgrade to these fixed versions to remediate the vulnerability. 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 indicated.
Description
A denial of service vulnerability exists in the pyasn1 BER/CER/DER decoder due to 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, oversized tag IDs can also trigger unhandled ValueErrors during error message formatting, potentially bypassing error handling. This affects applications decoding untrusted BER/CER/DER inputs using pyasn1 versions before 3.0.5 and 26.6.0_1. The issue is fixed in pyasn1 versions 3.0.5 and 26.6.0_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)