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Unratedamended

Integer underflow when reporting a malformed TSIG record

CVE-2026-123571GHSA-x962-5xwx-fr8x

What to do

Vendor fix available. Upgrade each affected package to the fixed version on its release line (hickory-proto 0.26.2), redeploy, then verify what is actually installed.

This page has no inventory attached, so it cannot say whether you are affected. A vendor fix is not proof that your deployment is fixed.

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Affected packages

Sources

Severity and exploitation
Exploitation
No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.
CVSS
not scored
EPSS
  • CVE-2026-123571: 0.41% estimated exploitation activity in the next 30 days; percentile 35.75 (FIRST EPSS, 2026-11-13). This is a model estimate, not proof of exploitation or customer exposure.
Source description

As published by the source; long descriptions are shortened.

When a TSIG record is decoded from the DNS wire format, its MAC length and "other data" length are checked against the end of the record data. If a check failed, the error value was built from `end_idx - decoder.index()`. For a malformed record the decoder can already be past `end_idx`, so this unsigned subtraction underflows. In builds with overflow checks enabled (the `dev` profile by default) the underflow panics, so a peer that sends a crafted TSIG record can crash the process. In builds without overflow checks the result wraps and is only used in the returned error. The fix returns a plain "insufficient bytes" error without the subtraction. It is in 0.26.2.

Dates and revisions
Published by the source
Last modified by the source
Source last checked
  1. Revision 2 · amended ·

    Amended from osv record RUSTSEC-2026-0488

  2. Revision 1 · created ·

    Published from osv record RUSTSEC-2026-0488

Agent brief

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

# Patch Next advisory brief: CVE-2026-123571

Advisory: Integer underflow when reporting a malformed TSIG record
IDs: CVE-2026-123571, GHSA-x962-5xwx-fr8x
Record: https://patchnext.com/advisories/rustsec-2026-0488 (revision 2, source checked 13 Nov 2026, 06:30 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Unrated
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: hickory-proto 0.26.2. A vendor fix does not mean a deployment is fixed.

## Affected components
- crates.io hickory-proto: affected >= 0.26.0, < 0.26.2; fixed in 0.26.2

## Suggested inspection (read-only)
- crates.io hickory-proto: 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 hickory-proto.
- 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-2026-0488 (OSV record RUSTSEC-2026-0488 lists affected ranges: crates.io hickory-proto >=0.26.0 <0.26.2 (fixed))

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