Description (CNA)
rustls-webpki through 0.103.12 (and 0.104.0-alpha releases before 0.104.0-alpha.7) contains a reachable panic in bit_string_flags() in src/der.rs. The input guard fails to reject a named-bit BIT STRING whose content is exactly [0x00] (zero padding bits and no data bytes), so raw_bits.len() - 1 underflows on the empty slice and the subsequent index operation panics (subtract-with-overflow in debug, index-out-of-bounds in release). The condition is reachable through the public API BorrowedCertRevocationList::from_der() when a CRL contains an issuingDistributionPoint extension with such an onlySomeReasons value. Exploitation requires an application that explicitly opts in to CRL revocation checking by passing RevocationOptions to verify_for_usage() and that parses CRL bytes obtained from a source the attacker can influence; the default rustls configuration, which does not use RevocationOptions, is unaffected. A crafted CRL causes a denial of service via the panic. Fixed in 0.103.13 and 0.104.0-alpha.7.
Affected (CNA)
| Vendor / product | Versions |
|---|---|
| rustls / webpki | affected 0 before 0.103.13; affected 0.104.0-alpha.1 before 0.104.0-alpha.7 |
CWE
CWE-191
References
- https://github.com/rustls/webpki/security/advisories/GHSA-82j2-j2ch-gfr8
- https://www.vulncheck.com/advisories/rustls-webpki-before-0.103.13-panic-via-empty-bit-string
ADP enrichment
No English description supplied.