CVE-2026-30922: pyasn1 is a generic ASN.1 library for Python
Affects pyasn1Source GCVE Database
Mentioned vulnerabilities
Not known to be exploited · CVSS 7.5 High · fixed in 0.1.7-1ubuntu2.1+esm1 : patch pyasn1 soon.
Data as of 26 Oct 2026, 14:05 UTC
- EPSS
- 0.8% chance of exploitation in 30 days – higher than 56% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 0.1.7-1ubuntu2.1+esm1, 0.1.9-1ubuntu0.1~esm1, 0.4.2-3ubuntu0.18.04.1~esm1 +4
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 18 Mar 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: 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 26 Oct 2026.
What to do
Upgrade to a fixed release listed under Affected software.
Patches and advisories
Affected software
| Product | Affected | Fixed in |
|---|---|---|
Ubuntu 25.10pyasn1pkg:deb/ubuntu/pyasn1?arch=source&distro=questingOther threats | Affected
| Fixed in
|
Ubuntu 24.04 LTSpyasn1pkg:deb/ubuntu/pyasn1?arch=source&distro=nobleOther threats | Affected
| Fixed in
|
Ubuntu 22.04 LTSpyasn1pkg:deb/ubuntu/pyasn1?arch=source&distro=jammyOther threats | Affected
| Fixed in
|
Ubuntu Pro 20.04 LTSpyasn1pkg:deb/ubuntu/pyasn1?arch=source&distro=esm-infra/focalOther threats | Affected
| Fixed in
|
Ubuntu Pro 18.04 LTSpyasn1pkg:deb/ubuntu/pyasn1?arch=source&distro=esm-infra/bionicOther threats | Affected
| Fixed in
|
Ubuntu Pro 16.04 LTSpyasn1pkg:deb/ubuntu/pyasn1?arch=source&distro=esm-infra/xenialOther threats | Affected
| Fixed in
|
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
Description
pyasn1 is a generic ASN.1 library for Python. Prior to 0.6.3, the `pyasn1` library is vulnerable to a Denial of Service (DoS) attack caused by uncontrolled recursion when decoding ASN.1 data with deeply nested structures. An attacker can supply a crafted payload containing thousands of nested `SEQUENCE` (`0x30`) or `SET` (`0x31`) tags with "Indefinite Length" (`0x80`) markers. This forces the decoder to recursively call itself until the Python interpreter crashes with a `RecursionError` or consumes all available memory (OOM), crashing the host application. This is a distinct vulnerability from CVE-2026-23490 (which addressed integer overflows in OID decoding). The fix for CVE-2026-23490 (`MAX_OID_ARC_CONTINUATION_OCTETS`) does not mitigate this recursion issue. Version 0.6.3 fixes this specific issue.
References
- ubuntu.com/security/CVE-2026-30922 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-30922 (opens in a new tab)
- github.com/pyasn1/pyasn1/security/advisories/GHSA-jr27-m4p2-rc6r (opens in a new tab)
- ubuntu.com/security/notices/USN-8129-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8134-1 (opens in a new tab)