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Public proof of conceptFix available

CVE-2020-1967

A public proof of concept exists; no exploitation attested.

  • Published2020-04-21
  • WeaknessCWE-476

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

Description

Server or client applications that call the SSL_check_chain() function during or after a TLS 1.3 handshake may crash due to a NULL pointer dereference as a result of incorrect handling of the "signature_algorithms_cert" TLS extension. The crash occurs if an invalid or unrecognised signature algorithm is received from the peer. This could be exploited by a malicious peer in a Denial of Service attack. OpenSSL version 1.1.1d, 1.1.1e, and 1.1.1f are affected by this issue. This issue did not affect OpenSSL versions prior to 1.1.1d. Fixed in OpenSSL 1.1.1g (Affected 1.1.1d-1.1.1f).

Timeline

dates in UTC
  1. 2020-04-2114:15CVE publishedNVD

Observed activity

isMalicious corpus · updated 2026-11-03 09:37 UTC
Indicators tagged with this CVE, per day0 indicators over 7 days
Block these indicators
  • Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2020-1967?format=txt
  • CSV export: https://api.ismalicious.com/edl/cve/CVE-2020-1967?format=csv
  • TAXII collection of exploited CVEs
  • The EDL and CSV take an API key on the Pro plan.

Versions per branch

NVD
OpenSSL
BranchAffectedFixed in
1.1≥ 1.1.1d, ≤ 1.1.1fno fix published
Oracle peoplesoft enterprise peopletools
BranchAffectedFixed in
8.56= 8.56no fix published
8.57= 8.57no fix published
8.58= 8.58no fix published
8.59= 8.59no fix published
Fedoraproject fedora
BranchAffectedFixed in
30.x= 30no fix published
31.x= 31no fix published
32.x= 32no fix published

24 more products in the sources.

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Products declared by the CNA1 product

As openssl, the CNA that assigned this CVE, declared them in the CVE record; versions as written.

  • OpenSSL
    Affected
    • = Fixed in OpenSSL 1.1.1g (Affected 1.1.1d-1.1.1f)no fix stated

Source: the CNA record (CVE Program), © The MITRE Corporation,CVE Terms of UseCVE recordupdated 2021-10-20

Distribution builds and vendor advisories

Packages from OSV.dev and products from the vendors' CSAF advisories.

version not verifiedVersions not verified: read as OSV.dev and the vendors publish them, not checked against each vendor's release list.

Packages

  • mysql-8.0Chainguardall versions · fixed in 8.0.38-r0and 4 other packages
  • opensslUbuntu:20.04:LTSall versions · fixed in 1.1.1f-1ubuntu2
  • opensslDebian:14all versions · fixed in 1.1.1g-1
  • opensslDebian:13all versions · fixed in 1.1.1g-1
  • opensslDebian:12all versions · fixed in 1.1.1g-1
  • opensslDebian:10all versions · fixed in 1.1.1d-0+deb10u3
  • opensslCleanStartall versions · fixed in 1.1.1g-r0and 1 other package
  • opensslAlpine:v3.24from 1.1.1d · fixed in 1.1.1g-r0

31 more package ranges on OSV.dev

Vendor advisories

  • CVE-2020-1967 Red Hat Product Security

    openssl: Segmentation fault in SSL_check_chain causes denial of service

  • ICSA-24-046-02 CISA1 known affected

    Siemens SIDIS Prime

    SIDIS Prime

  • SSA-108696 Siemens ProductCERT1 known affected

    SSA-108696: Multiple Vulnerabilities in SIDIS Prime before V4.0.400

    SIDIS Prime

Full record on NVD

Fix

  1. Vendor fix Siemens ProductCERT SSA-108696 · 1 productUpdate to V4.0.400 or later version
  2. Vendor fix CISA ICSA-24-046-02 · 1 productUpdate to V4.0.400 or later version

Advisories and patches

Detection

read 2026-11-02 22:42 UTC
Nuclei template
none so far
ProjectDiscovery
Exploit-DB
no entry
Exploit-DB
Proof-of-concept repositories
1 repository, unverifiedirsl/CVE-2020-1967
PoC-in-GitHub
Metasploit modules
none listed
Metasploit Framework

Sources

Identifiers

Technical details

CVSS v3 Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Published
2020-04-21
Last Modified
2026-10-08
NVD status
Modified
GitHub Advisory
GHSA-jq65-29v4-4x35

Frequently asked questions

What is CVE-2020-1967?

Server or client applications that call the SSL_check_chain() function during or after a TLS 1.3 handshake may crash due to a NULL pointer dereference as a result of incorrect handling of the "signature_algorithms_cert" TLS extension. The crash occurs if an invalid or unrecognised signature algorithm is received from the peer. This could be exploited by a malicious peer in a Denial of Service attack. OpenSSL version 1.1.1d, 1.1.1e, and 1.1.1f are affected by this issue. This issue did not affect OpenSSL versions prior to 1.1.1d. Fixed in OpenSSL 1.1.1g (Affected 1.1.1d-1.1.1f).

Is CVE-2020-1967 actively exploited?

Active exploitation of CVE-2020-1967 has not been confirmed. Its EPSS score was 53.3% on 2026-11-02, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2020-1967?

CVE-2020-1967 has a CVSS v3 base score of 7.5 (HIGH severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.

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Sources for this record