CVE & CISA-KEV Catalog

CVE-2026-45271

MEDIUM
5.5
CVSS v3
NVD

Description

Picotls is a TLS protocol library that allows users select different crypto backends based on their use case. Picotls implements its own ASN.1 validation helper, which is used by the minicrypto backend while parsing local PKCS#8 private keys. Prior to commit c14231d801407640bc42c2dcf92783409ea6a7c7, the validator recursively descends into constructed ASN.1 elements without enforcing a maximum nesting depth. If an application loads an attacker-supplied private-key file through ptls_minicrypto_load_private_key(), or otherwise calls the public ASN.1 validation API on untrusted DER, a crafted deeply nested ASN.1 structure can exhaust the process stack and crash the application. Note that the libcrypto (OpenSSL) backend does not use the ASN.1 validation helper of picotls, and therefore is immune to this vulnerability. The vulnerability has been addressed in commit c14231d801407640bc42c2dcf92783409ea6a7c7.

How to fix

No published remediation has been found for this vulnerability's affected products yet.

Mitigation guidance may be in the linked vendor advisories in the References section below.

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CVSS v3 Vector

Exploitability

Attack VectorLocal
Attack ComplexityLow
Privileges RequiredNone
User InteractionRequired
ScopeUnchanged

Impact

ConfidentialityNone
IntegrityNone
AvailabilityHigh

CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H

Exploit Intelligence

0.11%probability of exploitation in 30 days
2ndpercentile

Low risk: more likely to be exploited than 2% of all known CVEs.

References

Other references2

Related Vulnerabilities

Other CWE-835 vulnerabilities, ordered by exploit likelihood. View all

CVESeverityCVSSEPSSExploitedFix
CVE-2020-13935High7.587%-Fix
CVE-2020-36227High7.578%-Fix
CVE-2022-0778High7.573%-Fix
CVE-2024-20353High8.671%KEV-
CVE-2023-34966High7.562%-Fix
CVE-2019-14241High7.561%--

Common questions

How do I fix CVE-2026-45271?

No published fix for CVE-2026-45271 has been found yet. Check the linked vendor advisories for guidance as it becomes available.

Is CVE-2026-45271 being actively exploited?

Not that we know of. CVE-2026-45271 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 0.11% is the estimated probability that it will be exploited in the next 30 days. That is higher than 2% of all scored CVEs.

How severe is CVE-2026-45271?

CVE-2026-45271 has a CVSS v3 base score of 5.5, rated medium. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-08-21.