ALAS2023-2026-3375

References: CVE-2026-93599  CVE-2026-93600  CVE-2026-93601 
FAQs regarding Amazon Linux ALAS/CVE Severity

Issue Overview:

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. (CVE-2026-93599)

rustls-webpki (rustls/webpki) versions 0.101.0 through 0.103.11 and 0.104.0-alpha releases before 0.104.0-alpha.6 ignore X.509 name constraints that apply to URI names, causing such constraints to be accepted rather than enforced. Because name constraints are restrictions on otherwise properly issued certificates, the flaw is only reachable after successful signature verification and requires a misissued certificate to exploit; the library also provides no API for asserting URI names, and URI name constraints are otherwise unimplemented. Versions 0.103.12 and 0.104.0-alpha.6 reject URI name constraints unconditionally. (CVE-2026-93600)

rustls-webpki (the Rust webpki fork used by rustls) versions >= 0.101.0 and prior to 0.103.12 and 0.104.0-alpha.6 incorrectly accepted permitted-subtree DNS name constraints for certificates asserting a wildcard name. For example, a name constraint of accept.example.com was treated as satisfied by a certificate for *.example.com, which could feasibly assert reject.example.com -- a name outside the permitted subtree. Because name constraints are restrictions applied to otherwise properly issued certificates, the issue is only reachable after signature verification succeeds and requires a misissued wildcard certificate to exploit. (CVE-2026-93601)

Issue Correction:
Run dnf update aws-workload-credentials-provider --releasever 2023.12.20261109 or dnf update --advisory ALAS2023-2026-3375 --releasever 2023.12.20261109 to update your system.
More information on how to update your system can be found on this page: Amazon Linux 2023 documentation

New Packages:

aarch64:
    aws-workload-credentials-provider-debuginfo-3.1.2-1.amzn2023.aarch64
    aws-workload-credentials-provider-3.1.2-1.amzn2023.aarch64
    aws-workload-credentials-provider-debugsource-3.1.2-1.amzn2023.aarch64

src:
    aws-workload-credentials-provider-3.1.2-1.amzn2023.src

x86_64:
    aws-workload-credentials-provider-debuginfo-3.1.2-1.amzn2023.x86_64
    aws-workload-credentials-provider-3.1.2-1.amzn2023.x86_64
    aws-workload-credentials-provider-debugsource-3.1.2-1.amzn2023.x86_64