USN-8712-1: pyasn1 vulnerabilities
It was discovered that pyasn1 did not properly bound the size of long-form tag identifiers when parsing BER, CER, or DER encoded data. An attacker could possibly use this issue to cause applications decoding untrusted ASN.1 data to consume excessive CPU resources, resulting in a denial of service. (CVE-2026-59884) It was discovered that pyasn1 processed OBJECT IDENTIFIER and RELATIVE-OID values in quadratic time relative to the number of arcs. An attacker could possibly use this issue to cause applications decoding untrusted ASN.1 data to consume excessive CPU resources, resulting in a denial of service. (CVE-2026-59885) It was discovered that pyasn1 incorrectly handled conversion of decoded REAL values to Python float types. An attacker could possibly use this issue to cause applications decoding untrusted ASN.1 data to consume excessive CPU and memory resources, resulting in a denial of service. (CVE-2026-59886)
CSIRTS triage
- What
- pyasn1 has three denial-of-service vulnerabilities in BER/CER/DER parsing: unbounded long-form tag identifiers cause excessive CPU consumption, OBJECT IDENTIFIER processing is quadratic in arc count, and REAL value conversion causes excessive CPU and memory consumption.
- Who is affected
- Applications using pyasn1 to decode untrusted ASN.1 data are affected.
- Urgency
- Medium urgency as these are denial-of-service issues exploitable through untrusted input.
- Action
- Update pyasn1 to a patched version when available.
AI-assisted analysis generated from the source advisory — verify against the original.
⚡ Watch pyasn1
Get an email when a new pyasn1 advisory drops — max one per day, one-click unsubscribe.
Details
Original advisory: https://ubuntu.com/security/notices/USN-8712-1
Exploitation outlook
EPSS (FIRST.org) estimates each CVE’s probability of exploitation in the next 30 days — here is the CSIRTS.com read on those numbers.
- Low exploitation riskCVE-2026-598840.35% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 28% of all EPSS-scored CVEs.
- Low exploitation riskCVE-2026-598850.34% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 26% of all EPSS-scored CVEs.
- Low exploitation riskCVE-2026-598860.34% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 26% of all EPSS-scored CVEs.
Referenced CVEs
| CVE | CSIRTS overview | External |
|---|---|---|
| CVE-2026-59884 | coverage & exploitation status | NVD · CVE.org |
| CVE-2026-59885 | coverage & exploitation status | NVD · CVE.org |
| CVE-2026-59886 | coverage & exploitation status | NVD · CVE.org |
Same CVEs, other sources
How other CERTs, PSIRTs and databases cover the vulnerabilities in this advisory.
- medium[NEW] [medium] Red Hat Enterprise Linux (pyasn1): Vulnerability enables Denial of Servicecert-bund
- highGHSA-hm4w-wwcw-mr6r: pyasn1: Uncontrolled resource consumption when converting decoded REAL valuesghsa
- highGHSA-8ppf-4f7h-5ppj: pyasn1: Quadratic complexity in OBJECT IDENTIFIER and RELATIVE-OID processing allows deni…ghsa
- highGHSA-m4p7-r5rc-7g4j: pyasn1 BER/CER/DER decoder denial of service via unbounded long-form tag IDsghsa
- highCVE-2026-59886: pyasn1 is a generic ASN.1 library for Python. Prior to 0.6.4, the univ.Real type converted its…nvd
- highCVE-2026-59885: pyasn1 is a generic ASN.1 library for Python. Prior to 0.6.4, the BER, CER, and DER decoders p…nvd
- highCVE-2026-59884: pyasn1 is a generic ASN.1 library for Python. Prior to 0.6.4, the BER decoder shared by the CE…nvd
- highCVE-2026-59884: pyasn1 BER/CER/DER decoder denial of service via unbounded long-form tag IDsmsrc
- highCVE-2026-59885: pyasn1: Quadratic complexity in OBJECT IDENTIFIER and RELATIVE-OID processing allows denial of…msrc
- highCVE-2026-59886: pyasn1: Uncontrolled resource consumption when converting decoded REAL valuesmsrc
More from Ubuntu Security Notices
- unknownUSN-8717-1: Apache Tika vulnerability2026-09-03
- unknownUSN-8661-4: Linux kernel vulnerabilities2026-09-02
- unknownUSN-8715-1: Linux kernel (Oracle) vulnerabilities2026-09-02
- unknownUSN-8714-1: Linux kernel vulnerabilities2026-09-02
- unknownUSN-8713-1: BioSig vulnerabilities2026-09-02