CVE-2026-119195: pyasn1: Quadratic-time denial of service in constructed string and indefinite-length ANY decoding
Noroxi assessment
Priority: Monitor (action score 30/100)
- The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
- Probability of exploitation in the next 30 days: 0.52% (FIRST EPSS).
- Anyone who can reach it over the internet can trigger it. No account or password is required. No user action is required. No special conditions are required; it is repeatable.
- According to CISA the attack is automatable: targets can be found by mass scanning.
- Fixed version: pyasn1 pyasn1 0.6.5; azl3 python-pyasn1 0.4.8-3 on Azure Linux 3.0 Release Notes.
Low priority for now. Upgrade to pyasn1 pyasn1 0.6.5; azl3 python-pyasn1 0.4.8-3 on Azure Linux 3.0 Release Notes or later.
Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it
Primary sources: NVD · CVE.org · FIRST EPSS
pyasn1 is a generic ASN.1 library for Python. Prior to 0.6.5, constructed string and indefinite-length ANY decoding repeatedly concatenates each fragment onto a growing bytes value. Attacker-controlled BER or CER data can use many constructed OCTET STRING or character-string fragments. DER rejects constructed OCTET STRING without a schema, but accepts its definite-length form when asn1Spec selects univ.OctetString; it also accepts constructed character strings such as UTF8String without a schema, even though those encodings are not valid DER. The separate indefinite-length ANY path is reachable in BER and CER when asn1Spec selects univ.Any; DER rejects indefinite lengths. OctetStringPayloadDecoder uses growing header concatenation and AnyPayloadDecoder.indefLenValueDecoder uses growing chunk concatenation, repeatedly copying an increasing prefix and causing quadratic work. A sufficiently fragmented value can occupy decoding workers and cause CPU exhaustion without confidentiality or integrity impact. This issue is fixed in version 0.6.5.
- Published
- Oct 29, 2026
- Updated
- Oct 30, 2026
- EPSS
- 0.5% · 44th percentile
- CWE
- CWE-407
Report tools
Action score
30
Monitor
Low priority for now.
- CVSS
- 30 / 40 · 7.5 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 0 / 30 · 0.5%
CISA SSVC decision
- Exploitation
- proof of concept
- Automatable
- yes
- Technical impact
- partial
Vulnrichment: CISA's decision-tree inputs.
CNA vs NVD score
- NVD
- —
- CNA · GitHub_M
- 7.5
- NVD has not scored this yet; the score shown is the CNA’s.
The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.
Get told when this record changes
- Not in KEV: no record of exploitation in the wild
- No public exploit code on record
- A fix has been released
If any of these changes, we'll tell you in the daily email digest.
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Noroxi analysis
What does it mean in your environment?
The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.
We use this product, ask for helpAffected systems
Is your version affected?
Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.
—
Versions reported by the vendor
Affected version ranges reported by the assigning authority (GitHub_M). Independent of NVD's CPE analysis and usually ahead of it.
pyasn1 pyasn1
- < 0.6.5affected
Package-level exposure
OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.
| Ecosystem | Package | Affected range | Fix |
|---|---|---|---|
| Debian:12 | pyasn1 | from 0 | — |
| Debian:14 | pyasn1 | before 0.6.5-1 | 0.6.5-1 |
| PyPI | pyasn1 | before 0.6.5 | 0.6.5 |
Same product
pyasn1: all recordsOther highest-scoring records for the same primary product.
- CVE-2026-119197pyasn1: Quadratic-complexity denial of service in binary REAL decoding30Monitor
- CVE-2026-119196pyasn1: Quadratic CPU consumption in constructed BIT STRING decoding30Monitor
- CVE-2026-119194pyasn1: Quadratic CPU use in schemaless BER/CER/DER container decoding30Monitor
Published before and after this one in the same product
- ← EarlierCVE-2026-59884Jul 14, 2026 · pyasn1 BER/CER/DER decoder denial of service via unbounded long-form tag IDs30Monitor
- ← EarlierCVE-2026-59885Jul 14, 2026 · pyasn1: Quadratic complexity in OBJECT IDENTIFIER and RELATIVE-OID processing allows denial of service30Monitor
- ← EarlierCVE-2026-59886Jul 14, 2026 · pyasn1: Uncontrolled resource consumption when converting decoded REAL values30Monitor
Remediation
Which version to upgrade to
Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.
| Product / package | Fixed version | Source |
|---|---|---|
| pyasn1 pyasn1 | 0.6.5 · description | Vendor (CNA) |
| azl3 python-pyasn1 0.4.8-3 on Azure Linux 3.0 | Release Notes | Microsoft (MSRC) |
| debian:pyasn1 | 0.6.5-1 · Debian:14 | Package registry (OSV) |
| PyPI:pyasn1 | 0.6.5 | Package registry (OSV) |
Exploit status
No known public exploit
No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.
Research context
For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.
Timeline
From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.
- Published
- Fix recordedsame day
- TodayNov 5, 2026+7 d
FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).
Patch and commit links
Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.
Credits
All researchersFinders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.
No credits in the CNA record.
Variant candidates
Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.
- CVE-2026-1191940 days apartpyasn1: Quadratic CPU use in schemaless BER/CER/DER container decoding30Monitor
- CVE-2026-1191960 days apartpyasn1: Quadratic CPU consumption in constructed BIT STRING decoding30Monitor
- CVE-2026-1191970 days apartpyasn1: Quadratic-complexity denial of service in binary REAL decoding30Monitor
Chain candidates
An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.
—
Bug bounty scope
No known public program.
Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).
Technical details
Attack conditions
- Anyone who can reach it over the internet can trigger it.
- No account or password is required.
- No user action is required.
- No special conditions are required; it is repeatable.
If successful
- Confidentiality
- none
- Integrity
- none
- Availability
- high · the service can be disrupted
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality impact
- None
- Integrity impact
- None
- Availability impact
- High
Weakness class (CWE)
CWE-407 · Inefficient Algorithmic ComplexityCVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
nvd-secondary
Attack context
MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.
MITRE has no CAPEC/ATT&CK mapping for this CWE.
Change log
- SSVC exploitation— → poc
- Exploit maturity— → none
- Fix✗ → ✓
For records you follow, these changes also arrive as notifications. →
References
Show all references (3 more)Show less
Vendor advisories and official records. Exploit/PoC links are deliberately left out.