Application crash via unsupported signature algorithm
Published Apr 21, 2020 · Updated Sep 17, 2024
NULL pointer dereference in OpenSSL 1.1.1d through 1.1.1f allows remote attackers to crash TLS 1.3 applications via a crafted extension. In tls1_check_sig_alg(), an unsupported peer value makes tls1_lookup_sigalg() return NULL, and the result is dereferenced unconditionally. Only applications that call SSL_check_chain() during or after a TLS 1.3 handshake expose the path; a malicious peer can terminate the process.
Summary
What happened
NULL pointer dereference in OpenSSL 1.1.1d through 1.1.1f allows remote attackers to crash TLS 1.3 applications via a crafted extension. In tls1_check_sig_alg(), an unsupported peer value makes tls1_lookup_sigalg() return NULL, and the result is dereferenced unconditionally. Only applications that call SSL_check_chain() during or after a TLS 1.3 handshake expose the path; a malicious peer can terminate the process.
The record
- CVE
- CVE-2020-1967
- Published
- Apr 21, 2020
- Updated
- Sep 17, 2024
- Vendor
- OpenSSL Project
- Product
- OpenSSL
- Classifications
- CWE-476, T1499.004
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Apr 21, 2020CVE publishedPublication date reported by the CVE source.
- Sep 17, 2024Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=Fixed in OpenSSL 1.1.1g (Affected 1.1.1d-1.1.1f)
What conditions does exploitation require?
What is affected?
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
- CVE-2020-1967 signature_algorithms_cert denial-of-service proof of conceptproof of concept · demonstrated
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Technologies
Your stack
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Your stack
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