MIKEY message MAC is never verified on receive, so forged messages are accepted

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

7.5 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

EPSS

No dated EPSS signal available.

As published by the source; long descriptions are shortened.

`mykey` implements MIKEY (RFC 3830) for SRTP key exchange. No receive path verified the MIKEY message authentication code. `crypto::verify_mac` existed and was correct, but it was called only from unit tests — neither `MikeyMessage::from_bytes` nor `MikeyMessage::complete_psk` invoked it. `new_psk_init` computed an HMAC-SHA-1-160 over the serialized message and appended it, so the tag was present on the wire and looked like integrity protection. It was decorative: a receiver accepted any message regardless of whether the MAC was correct, wrong, or absent.

Consequences - An attacker able to inject or modify MIKEY messages in transit faced no integrity check. Modified RAND, SSRC or security-policy payloads were accepted silently. Note that this does not require a man-in-the-middle position: since nothing was checked, a wholly forged PSK-Init was accepted. - Pre-shared key mode therefore provided no mutual authentication, despite the documentation claiming that it did. Possession of…

Published by the source

9 Oct 2026, 12:00 UTC

Last modified by the source

12 Oct 2026, 09:15 UTC

Source last checked

23 Oct 2026, 22:04 UTC

1. Revision 1 · created · 24 Oct 2026

   Published from osv record RUSTSEC-2026-0336

Preview the exact text before you copy it. Commands are read-only suggestions; review them before running anything.

# Patch Next advisory brief: GHSA-xq78-wvcv-hqvj

Advisory: MIKEY message MAC is never verified on receive, so forged messages are accepted
IDs: GHSA-xq78-wvcv-hqvj
Record: https://patchnext.com/advisories/rustsec-2026-0336 (revision 1, source checked 23 Oct 2026, 22:04 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 7.5)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: mykey 2.0.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- crates.io mykey: affected >= 0.0.0-0, < 2.0.0; fixed in 2.0.0

## Suggested inspection (read-only)
- crates.io mykey: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on mykey.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/RUSTSEC-2026-0336 (OSV record RUSTSEC-2026-0336 lists affected ranges: crates.io mykey >=0.0.0-0 <2.0.0 (fixed))

Commands are suggestions: review each one before running it.