{"id":"CVE-2026-93599","title":"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","summary":"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] (ze…","severity":"high","cvss":7.5,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","cwe":["CWE-191","CWE-125"],"vendor":"rustls","product":"webpki","affected":["webpki < 0.103.13","webpki >= 0.104.0-alpha.1 < 0.104.0-alpha.7"],"patched":["rustls-webpki 0.104.0-alpha.7"],"published":"2026-09-18","updated":"2026-09-22","sourceUpdated":"2026-09-22T20:25:55.870","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-93599","references":[{"url":"https://github.com/rustls/webpki/security/advisories/GHSA-82j2-j2ch-gfr8","label":"disclosure@vulncheck.com"},{"url":"https://www.vulncheck.com/advisories/rustls-webpki-before-0.103.13-panic-via-empty-bit-string","label":"disclosure@vulncheck.com"},{"url":"https://github.com/rustls/webpki/security/advisories/GHSA-82j2-j2ch-gfr8","label":"134c704f-9b21-4f2e-91b3-4a467353bcc0"},{"url":"https://crates.io/crates/rustls-webpki"},{"url":"https://rustsec.org/advisories/RUSTSEC-2026-0104.html"},{"url":"https://github.com/rustls/webpki"},{"url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-93599.json"},{"url":"https://access.redhat.com/security/cve/CVE-2026-93599"},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2538431"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-93599"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-93599"},{"url":"https://access.redhat.com/errata/RHSA-2026:56999"},{"url":"https://access.redhat.com/errata/RHSA-2026:66076"},{"url":"https://access.redhat.com/errata/RHSA-2026:42825"},{"url":"https://access.redhat.com/errata/RHSA-2026:57200"},{"url":"https://access.redhat.com/errata/RHSA-2026:70694"}],"tags":["nvd","cve.org","exploit-available","osv","rust","csaf","vex","red-hat"],"epss":0.00488,"epssPercentile":0.39321,"aliases":["RUSTSEC-2026-0104","GHSA-82j2-j2ch-gfr8"],"ecosystem":"rust","exploitAvailable":true,"ssvc":{"exploitation":"poc","automatable":"yes","technicalImpact":"partial","timestamp":"2026-09-18T14:04:54.272751Z"},"ingestedAt":"2026-09-18T13:41:41.663Z","slug":"CVE-2026-93599","body":"## Overview\n\nrustls-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.\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.\n\n## Package advisory (CVE-2026-93599)\n\nAffected packages:\n\n- `rustls-webpki >= 0.104.0-alpha.1, < 0.104.0-alpha.7`\n\nPatched in:\n\n- `rustls-webpki 0.104.0-alpha.7`\n\nSource: https://osv.dev/vulnerability/RUSTSEC-2026-0104\n\n## Vendor advisories\n\n- **Red Hat VEX** · Important · affected: Ansible Automation Orchestrator 2026, Confidential Cluster Operator, Logging Subsystem for Red Hat OpenShift, Migration Toolkit for Applications 8, OpenShift Lightspeed, Red Hat Ansible Automation Platform 2, … · no fix planned: OpenShift Lightspeed, Red Hat Ansible Automation Platform 2, Red Hat Trusted Profile Analyzer, Ansible Automation Orchestrator 2026, … · updated 2026-09-25 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-93599.json)\n- **RHSA-2026:56999** · Red Hat · fixed in: Red Hat Hardened Images · released 2026-08-19 · [advisory](https://access.redhat.com/errata/RHSA-2026:56999)\n- **RHSA-2026:66076** · Red Hat · fixed in: Red Hat Hardened Images · released 2026-09-09 · [advisory](https://access.redhat.com/errata/RHSA-2026:66076)\n- **RHSA-2026:42825** · Red Hat · fixed in: Red Hat Hardened Images · released 2026-07-21 · [advisory](https://access.redhat.com/errata/RHSA-2026:42825)\n- **RHSA-2026:57200** · Red Hat · fixed in: Red Hat Hardened Images · released 2026-08-20 · [advisory](https://access.redhat.com/errata/RHSA-2026:57200)\n- **RHSA-2026:70694** · Red Hat · fixed in: Red Hat Hardened Images · released 2026-09-23 · [advisory](https://access.redhat.com/errata/RHSA-2026:70694)","depth":"midnight","depthScore":53,"depthScoreParts":{"impact":41.3,"likelihood":0.1,"exploitation":12,"ransomware":0},"changes":[{"seq":206866,"id":"CVE-2026-93599","ts":1789742654538,"field":"exploit_available","old":"false","new":"true"}]}