{"answers":{"affected":"1 open source package ship an affected version, including pqc_kyber.","exploited":"There is no known exploitation of RUSTSEC-2026-0290 in the wild and no public exploit code.","fix":"No fix has been published for RUSTSEC-2026-0290 yet. Limit exposure of the affected software until one is available.","what":"RUSTSEC-2026-0290 is a vulnerability in pqc_kyber, published on 16 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim."},"fix_prompt":"Check this codebase for RUSTSEC-2026-0290 and fix it if it is affected.\n\nWhat it is: RUSTSEC-2026-0290 is a vulnerability in pqc_kyber, published on 16 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.\nExploitation: There is no known exploitation of RUSTSEC-2026-0290 in the wild and no public exploit code.\n\nAffected packages and fixed versions:\n- pqc_kyber (crates.io): affected from 0.0.0-0; no fix listed\n\nTask:\n1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.\n2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.\n3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.\n4. Run the tests and summarise what changed and why.\n5. If nothing in the project is affected, say so and change nothing.\n\nReference: https://insights.sbomify.com/RUSTSEC-2026-0290/ (Markdown: https://insights.sbomify.com/RUSTSEC-2026-0290/index.md)","id":"RUSTSEC-2026-0290","markdown":"https://insights.sbomify.com/RUSTSEC-2026-0290/index.md","name":"RUSTSEC-2026-0290","record":{"aliases":[],"analysis":{"component_type":"library","fix_type":"configuration_change","impacts":["data_read","privilege_escalation"],"network_reachable":"yes","non_default_config":true,"product_category":"Rust Kyber library","requires_auth":"none","summary":"Enabling the AVX2 feature in pqc_kyber breaks implicit rejection, allowing attackers to recover static secret keys via chosen-ciphertext attacks.","user_interaction":"not_required","vuln_class":"weak_cryptography"},"analysis_generated_by":"qwen3.8-flash-next","assigner":null,"cpe":[],"cvss":{"score":null,"severity":null,"source":null,"vector":null,"version":null},"cwes":[],"description":"## Summary\n\nWhen `pqc_kyber` is built with the opt-in `avx2` feature on x86_64, its\nconstant-time conditional-move routine `cmov` is a no-op: it never performs the\ncopy. That `cmov` is exactly the step that applies the Fujisaki-Okamoto (FO)\nimplicit rejection during decapsulation. With it disabled, decapsulating an\n*invalid* ciphertext no longer returns a key-independent pseudorandom value;\nit returns a value that depends on the decrypted plaintext of the\nattacker-chosen ciphertext. This restores the chosen-ciphertext decryption\noracle that the FO transform exists to remove, and yields full recovery of the\nstatic secret key.\n\nThe attack requires no timing measurement, no side channel, and no faults; only\nthe ability to submit ciphertexts to a decapsulation operation under a reused\nkey pair and observe the resulting shared secret. See the linked pull request\nfor the root cause, the reachable call path, and reproduction details.\n\n## Affected configuration\n\nReachable only in builds with `features = [\"avx2\"]` on an x86_64 target. The\ndefault (reference) backend and all non-x86_64 targets are unaffected.\n\n## Impact\n\nComplete IND-CCA break. The plaintext-checking oracle drives a standard\nchosen-ciphertext key-recovery attack and extracts the entire static secret\nkey. Any protocol reusing a Kyber key pair across decapsulations (static or\nlong-term KEM keys, KEMTLS, HPKE recipients, pinned keys) is exposed;\nephemeral-only key shares are not. The defect was verified end to end on\nML-KEM-768: the full secret key was recovered in 4,272 decapsulation queries.\n\n## Maintenance status\n\nThe crate is unmaintained (last release 0.7.1, August 2023); no patched version\nexists or is expected.\n\n## Mitigation\n\n- If remaining on this crate, do not enable the `avx2` feature; the default\n  reference backend performs implicit rejection correctly.\n- Do not reuse a Kyber key pair across decapsulations.\n\n## Credit\n\nReported by 007bsd.","ecosystems":["crates.io"],"exploits":{"exploitdb":null,"first_seen":null,"github_poc":null,"max_poc_stars":null,"metasploit":null,"nuclei":null,"refs":[],"tier":null},"has_fix":false,"headline":"pqc_kyber: AVX2 backend skips Fujisaki-Okamoto implicit rejection, enabling chosen-ciphertext key recovery","id":"RUSTSEC-2026-0290","indexable":true,"kev":null,"kind":"advisory","links":{"ecosystem":"crates.io","product":null,"products":[],"type":"weak_cryptography","year":"2026"},"n_packages":1,"n_references":null,"packages":[{"ecosystem":"crates.io","fixed":[],"introduced":["0.0.0-0"],"last_affected":[],"package":"pqc_kyber","purl":"pkg:cargo/pqc_kyber","source":"RUSTSEC-2026-0290"}],"products":null,"published":"2026-08-16","related":[],"sources":[{"class":"open","licence":"CC0 1.0","name":"RustSec","prefix":"RUSTSEC"}],"ssvc":{"automatable":null,"exploitation":null,"technical_impact":null},"state":null,"updated":null,"vendors":null},"summary":"Enabling the AVX2 feature in pqc_kyber breaks implicit rejection, allowing attackers to recover static secret keys via chosen-ciphertext attacks.","url":"https://insights.sbomify.com/RUSTSEC-2026-0290/"}