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CVE-2026-123571

Integer underflow when reporting a malformed TSIG record

Products / packages hickory-dns · hickory-proto

Published

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Severity and exploitation

Not in CISA KEV

KEV coverage does not rule out exploitation.

KEV checked 15/11/2026, 01:25:32 UTC
VulnCheck · CVSS:4.0 · 8.7
Assessment vectorCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
VulnCheck · CVSS:3.1 · 7.5
Assessment vectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
The headline uses the highest imported catalog score. Assessments can differ by source and CVSS version.

Severity

high8.7

CVSS measures technical severity, not the likelihood of an attack.

Known exploitation

Not listed in the checked CISA KEV catalog

Absence from CISA KEV does not rule out attacks.

Public exploit

Not established by this record

Missing evidence does not mean no public exploit exists.

Remediation

Package fixes recorded

Fix versions are recorded for 1 of 1 mapped packages. Check each release branch and any separate product guidance.

What this means

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.

Source excerpt · OSV

Attack conditions

No attack-condition excerpt has been identified here. Review the full source description and references for authentication, network access, and configuration requirements.

Review supporting sources →

Affected versions

Check the exact model, release, and any platform requirements against your installation.

hickory-dns · VulnCheck

hickory-dns

2 ranges
VulnCheck version evidence

Package identity

pkg:cargo/hickory-protoExplore hickory-proto →

Identity supplied by VulnCheck. Version matching requires compatible range evidence.

Compare with this publisher’s ranges. This does not inspect your installation.

affected

0.26.0 → before 0.26.2

semver versions

unaffected

0.26.2

semver versions

unknown

Other versions: unaffected

Packages

Compare each installed version with the publisher’s affected ranges. Where a fix is recorded, choose the appropriate release branch and test compatibility before upgrading.

hickory-proto crates.io
Affected range Recorded fix
From 0.26.0 before 0.26.2Semantic versions0.26.2

Version evidence: OSV · RUSTSEC-2026-0488

View original version evidence (0 explicit versions)

What to do

Compare your installed product and version with the affected versions above. A matching product name alone does not confirm exposure.

Use the recorded fix for your release branch. Review the publisher’s instructions and test compatibility before upgrading.

cve.new guidance unless attributed to a publisher. This page does not inspect your installation.

Public exploit evidence

No public exploit reference is identified in the imported evidence. This is not a claim that no exploit exists.

Original source description

Read the full publisher description

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.

References

5 sources
hickory-dns/hickory-dns · security/advisories/GHSA-x962-5xwx-fr8x
Vendor advisoryVulnCheck
crates.io/crates/hickory-proto
Source reference
rustsec.org/advisories/RUSTSEC-2026-0488.html
Security advisory
hickory-dns/hickory-dns · commit b1246a8
Patch
www.vulncheck.com/advisories/hickory-dns-from-0.26.0-before-0.26.2-panic-via-tsig-rdata-decoding
Security advisoryVulnCheck

Inside the record

Evidence available

Package identity
Version evidence
Remediation guidance · not supplied
Weakness classification
Additional publishers

Describes the evidence in this view, not whether the product is safe.

Original records

CVE-2026-123571

View the latest unmodified CVE JSON from the official source. It may be newer than this imported page.

cve.new JSON →

Underlying weaknesses

The source’s classification of what caused the vulnerability.

CWE-191 ↗

Integer Underflow (Wrap or Wraparound)

VulnCheck

Related →
Contributing organizations · 2
VulnCheck

Assigning organization

2026-11-08
CISA-ADP

Additional data publisher

2026-11-13

Timeline

All times UTC

  1. Advisory published

    Publication date supplied by the source.

  2. Source updated

    Latest modification date supplied by the source.

  3. Last imported by cve.new

    Latest catalog import, not the date we first saw this advisory.

What changed

Follow changes
  1. CVE · CVE-2026-123571

    Observed 2026-11-13T06:57:20.345Z · upstream updated 2026-11-13T03:04:27.566Z

    Prioritization updated

    before

    []

    after

    [
  {
    "source": "CISA-ADP",
    "type": "SSVC",
    "role": "CISA Coordinator",
    "timestamp": "2026-11-13T03:04:18.930667Z",
    "decisions": [
      {
        "name": "Exploitation",
        "value": "none"
      },
      {
        "name": "Automatable",
        "value": "yes"
      },
      {
        "name": "Technical Impact",
        "value": "partial"
      }
    ]
  }
]

Large field values are marked as truncated previews. Original source snapshots remain retained.

Showing up to 50 most recent observed changes.