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VulnerabilityPublished Updated

CVE-2026-59884: S3ql · pyasn1 BER/CER/DER decoder denial of service via unbounded long-form tag IDs

Affects s3qlSource GCVE Database

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Not known to be exploited · CVSS 7.5 High : upgrade to 6.2.2_1 or 3.8.1 soon.

Data as of 1 Nov 2026, 01:50 UTC

CVSS 3.1 base score
7.5High
How severe the flaw is on the 0–10 CVSS scale.
Patch
Available – fixed in 6.2.2_1, 3.8.1
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 13 Aug 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq 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 s3ql to 6.2.2_1 or 3.8.1.

Affected software

ProductAffectedFixed in
Homebrews3qlpkg:brew/s3qlOther threatsAffected
  • >=3.1 <3.8.1
  • >=6.0.0 <6.2.2_1
Fixed in
  • 3.8.1
  • 6.2.2_1

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

Apply the official patch by upgrading pyasn1 to version 0.6.4 or later, where long-form tag IDs are limited and oversized tags are rejected with PyAsn1Error. Alternatively, bound the size of untrusted input before passing it to decode() to prevent excessive resource consumption.

Description

A denial of service vulnerability exists in the pyasn1 BER/CER/DER decoder used by s3ql, caused by unbounded long-form tag IDs. The decoder accumulates continuation octets without an upper limit, allowing crafted inputs to cause excessive CPU usage. On Python 3.11 and later, this can also trigger unhandled ValueError exceptions, potentially bypassing error handling. The issue affects decoding of untrusted BER/CER/DER inputs and was fixed in pyasn1 version 0.6.4 by limiting tag ID length and improving error handling.

References

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