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VulnerabilityPublished Updated

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

Affects aws-shellSource GCVE Database

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Not known to be exploited · CVSS 7.5 High : upgrade to 0.2.2_15 soon.

Data as of 1 Nov 2026, 02:07 UTC

CVSS 3.1 base score
7.5High
How severe the flaw is on the 0–10 CVSS scale.
Patch
Available – fixed in 0.2.2_15
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 aws-shell to 0.2.2_15.

Affected software

ProductAffectedFixed in
Homebrewaws-shellpkg:brew/aws-shellOther threatsAffected
  • >=0.1.0 <0.2.2_15
Fixed in
  • 0.2.2_15

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 version 0.2.2_15 that 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 decode() 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 aws-shell, caused by unbounded long-form tag IDs. The decoder accumulates continuation octets without an upper limit, allowing crafted inputs to cause excessive CPU consumption and potential unhandled exceptions on Python 3.11+. This affects decoding of untrusted BER/CER/DER inputs. The issue is fixed in version 0.2.2_15 by limiting tag ID size and improving error handling.

References

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