Vulnerability · CVE-2026-119195
pyasn1 has quadratic-time denial of service in constructed string and indefinite-length ANY decoding
Published Oct 30, 2026 · catalog updated Oct 30, 2026 · pyasn1 has quadratic-time denial
Last checked Nov 6, 2026. A connected source was read within the last 7 days.
Check if you run it
No confirmed exploitation is on record for CVE-2026-119195. EPSS is 0.53%. Act only if a listed version of pyasn1 has quadratic-time denial is installed.
Gaps on this record
- The stored product name is a package slug. The name on this page is taken from the title (pyasn1 has quadratic-time denial).
- No vendor fix or required action is stored. Compare the linked advisory before you change production.
- Severity
- High7.5
- Known exploitation
- Not in CISA/VulnCheck KEV
- EPSS
- 0.53%
- Remediation
- Version ranges on file
- Affected products
- PyPI pyasn1 · pip pyasn1 · pypi pyasn1
## Summary In pyasn1 0.6.4 and earlier, decoding a constructed OCTET STRING or character string made of many fragments can spend disproportionate CPU time repeatedly copying the accumulated value. A separate indefinite-length path has the same problem while collecting the encoded components. The work grows roughly quadratically with the number of fixed-size fragments, although the input and decoded value grow linearly. An application that lets an attacker supply such ASN.1 input to an affected decoder can suffer CPU exhaustion. The affected string paths are available in BER and CER. The DER decoder also accepts certain *non-DER* constructed strings: a definite-length constructed OCTET STRING when an selects , and constructed character strings such as UTF8String even without a schema. Indefinite-length is affected in BER and CER when an selects ; DER rejects indefinite lengths. This is a distinct decoder path from the OBJECT IDENTIFIER/RELATIVE-OID accumulation addressed by [CVE-2026-59885](https://github.com/advisories/GHSA-8ppf-4f7h-5ppj). It has the same complexity class, but the OID fix in 0.6.4 did not change these string or loops. ## Technical details In the [v0.6.4 BER decoder](https://github.com/pyasn1/pyasn1/blob/v0.6.4/pyasn1/codec/ber/decoder.py), appends each decoded fragment to a growing value with in both its [definite-length](https://github.com/pyasn1/pyasn1/blob/v0.6.4/pyasn1/codec/ber/decoder.py#L338-L351) and [indefinite-length](https://github.com/pyasn1/pyasn1/blob/v0.6.4/pyasn1/codec/ber/decoder.py#L368-L387) constructed forms. [ ](https://github.com/pyasn1/pyasn1/blob/v0.6.4/pyasn1/codec/ber/decoder.py#L1403-L1430) similarly uses . In the exercised paths, each concatenation copies an increasingly large prefix. For fixed-size fragments, the total copied data grows with , or O(N²). The OCTET STRING decoder is also the base class of the decoders for UTF8String, NumericString, PrintableString, TeletexString, VideotexString, IA5String, GraphicString,
Are you affected?
Enter the version you run. The result uses only the ranges stored on this record.
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- PyPI pyasn10 → 0.6.5
- pip pyasn1<= 0.6.4
- pypi pyasn1version unspecified
How to fix CVE-2026-119195
Upgrade
CVE-2026-119195 lists a fix boundary at 0.6.5. Compare the installed build with that boundary before you change production.
Version check
Affected <= 0.6.4
Advisory
Open the cve_org record and follow its fix.
Official advisories
What to do
Three questions, each answered from this record only. Confirm the vendor advisory before you patch.
Should you patch?
No confirmed exploitation is on record for CVE-2026-119195. EPSS is 0.53%. Act only if a listed version of pyasn1 has quadratic-time denial is installed.
Which versions are affected?
Compare what you have installed with 0 → 0.6.5, <= 0.6.4. Compare the installed version with the linked vendor advisory before you change production.
What should an analyst verify?
CWE-407. EPSS 0.53%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.
Code
The project this record applies to. Exploit listings stay in References.
Timeline
Detection, updates, and resolution for this record.
Oct 30, 2026 · GitHub Advisory Database
Detected
## Summary In pyasn1 0.6.4 and earlier, decoding a constructed OCTET STRING or character string made of many fragments can spend disproportionate CPU time repeatedly copying the accumulated value. A separate indefinite-length path has the same problem while collecting the encoded components. The work grows roughly quadratically with the number of fixed-size fragments, although the input and decode
Oct 30, 2026 · GitHub Advisory Database
Updated
## Summary In pyasn1 0.6.4 and earlier, decoding a constructed OCTET STRING or character string made of many fragments can spend disproportionate CPU time repeatedly copying the accumulated value. A separate indefinite-length path has the same problem while collecting the encoded components. The work grows roughly quadratically with the number of fixed-size fragments, although the input and decode
Oct 30, 2026 · PyPA Advisory Database
Fix available
pyasn1 fixed in 0.6.5
Oct 30, 2026 · PyPA Advisory Database
Fix available
pyasn1 fixed in 0.6.5
Oct 30, 2026 · PyPA Advisory Database
Updated
## Summary In pyasn1 0.6.4 and earlier, decoding a constructed OCTET STRING or character string made of many fragments can spend disproportionate CPU time repeatedly copying the accumulated value. A separate indefinite-length path has the same problem while collecting the encoded components. The work grows roughly quadratically with the number of fixed-size fragments, although the input and decode
Sources
- CVE.orgVulnerability recordCVE-2026-119195
Official CVE identifier
cve.org - GitHub Advisory DatabasePackage advisoryGHSA-9m75-vc3g-4x39
pyasn1 has quadratic-time denial of service in constructed string and indefinite-length ANY decoding
github.com - GitLab Advisory DatabasePackage advisoryCVE-2026-119195
In pyasn1 0.6.4 and earlier, decoding a constructed OCTET STRING or character string made of many fragments can spend disproportionate CPU time repeatedly copying the accumulated value. A separate indefinite-length ANY path has the same problem while collecting the encoded components. The work grows roughly quadratically with the number of fixed-size fragments, although the input and decoded value
advisories.gitlab.com - PyPA Advisory DatabasePackage advisoryGHSA-9m75-vc3g-4x39
pyasn1 has quadratic-time denial of service in constructed string and indefinite-length ANY decoding
osv.dev
References
Freshness
Last verified in this catalog Nov 6, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.
- GitHub Advisory DatabaseNov 6, 2026
- GitLab Advisory DatabaseNov 3, 2026
- PyPA Advisory DatabaseNov 2, 2026
- CVE.orgOct 31, 2026