Memory over-read and crashes via undersized tags
Published May 27, 2021 · Updated Aug 4, 2024
Out-of-bounds reads in Mozilla NSS before 3.55 allow attackers to read adjacent memory or crash consumers via undersized ChaCha20-Poly1305 tags. The PKCS #11 decryption caller accepts tags shorter than the required 16 bytes and passes them to Hacl_Chacha20Poly1305_256_aead_decrypt, which reads past the tag buffer. Reachability requires a consuming application to invoke that path with an undersized tag; Mozilla reports that ordinary TLS and WebCrypto paths are unaffected.
Summary
What happened
Out-of-bounds reads in Mozilla NSS before 3.55 allow attackers to read adjacent memory or crash consumers via undersized ChaCha20-Poly1305 tags. The PKCS #11 decryption caller accepts tags shorter than the required 16 bytes and passes them to Hacl_Chacha20Poly1305_256_aead_decrypt, which reads past the tag buffer. Reachability requires a consuming application to invoke that path with an undersized tag; Mozilla reports that ordinary TLS and WebCrypto paths are unaffected.
The record
- CVE
- CVE-2020-12403
- Published
- May 27, 2021
- Updated
- Aug 4, 2024
- Vendor
- Mozilla
- Product
- Network Security Services (NSS)
- Classifications
- CWE-125
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- May 27, 2021CVE publishedPublication date reported by the CVE source.
- Aug 4, 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?
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- Affected versionversion=nss 3.55
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
- chacha20_oob_read.cppproof of concept · demonstrated
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Technologies
Your stack
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Your stack
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