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NVD / CVE Program· CNA Linux

CVE-2026-31676: rxrpc: only handle RESPONSE during service challenge

Noroxi assessment

Priority: Monitor (action score 30/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.47% (FIRST EPSS).
  • Anyone who can reach it over the internet can trigger it. No account or password is required. No user action is required. No special conditions are required; it is repeatable.
  • According to CISA the attack is automatable: targets can be found by mass scanning.
  • Fixed version: Linux Linux 03fd2ef73cb4ffd0af100a95b634af54f474414e, 0afdfd4941c1b60a1f5c361760daa970edca60cd, 29b44d904dceb832be880def08b8cb17a0aba91c; azl3 kernel 6.6.134.1-2 on Azure Linux 3.0 6.6.137.1-1.

Low priority for now. Upgrade to Linux Linux 03fd2ef73cb4ffd0af100a95b634af54f474414e, 0afdfd4941c1b60a1f5c361760daa970edca60cd, 29b44d904dceb832be880def08b8cb17a0aba91c; azl3 kernel 6.6.134.1-2 on Azure Linux 3.0 6.6.137.1-1 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

In the Linux kernel, the following vulnerability has been resolved: rxrpc: only handle RESPONSE during service challenge Only process RESPONSE packets while the service connection is still in RXRPC_CONN_SERVICE_CHALLENGING. Check that state under state_lock before running response verification and security initialization, then use a local secured flag to decide whether to queue the secured-connection work after the state transition. This keeps duplicate or late RESPONSE packets from re-running the setup path and removes the unlocked post-transition state test.

HighCVSS 7.5 · v3.1—No exploit Fix available
Published
Apr 25, 2026
Updated
Oct 19, 2026
EPSS
0.4% · 41th percentile

Report tools

JSON

Action score

30

Monitor

Low priority for now.

CVSS
30 / 40 · 7.5 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.4%

CISA SSVC decision

Exploitation
none
Automatable
yes
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
—
CNA · Linux
7.5
NVD has not scored this yet; the score shown is the CNA’s.

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

If any of these changes, we'll tell you in the daily email digest.

Follow CVE-2026-31676

When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
linuxlinux kernel

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • linux linux kernel2.6.22 and later · before 6.6.136
  • linux linux kernel6.7 and later · before 6.12.84
  • linux linux kernel6.13 and later · before 6.18.23
  • linux linux kernel6.19 and later · before 6.19.13
  • linux linux kernel7.0

Versions reported by the vendor

Affected version ranges reported by the assigning authority (Linux). Independent of NVD's CPE analysis and usually ahead of it.

  • Linux Linux

    • 2.6.22affected
    • 17926a79320afa9b95df6b977b40cca6d8713cea and later · before a1a8efde03a40b6c658d580e96644d9b9a2a0d3aaffected · git
    • 17926a79320afa9b95df6b977b40cca6d8713cea and later · before 6c3a0fbdafef8316e34ae22333e317a341e737cdaffected · git
    • 17926a79320afa9b95df6b977b40cca6d8713cea and later · before 0afdfd4941c1b60a1f5c361760daa970edca60cdaffected · git
    • 17926a79320afa9b95df6b977b40cca6d8713cea and later · before a6bcf8010af093fe04f7100562e9542ab7882585affected · git
    • 17926a79320afa9b95df6b977b40cca6d8713cea and later · before 29b44d904dceb832be880def08b8cb17a0aba91caffected · git
    • 17926a79320afa9b95df6b977b40cca6d8713cea and later · before d0035e634dae83237ab7f5681eb52b2f65d0ceb8affected · git
    • 17926a79320afa9b95df6b977b40cca6d8713cea and later · before 03fd2ef73cb4ffd0af100a95b634af54f474414eaffected · git
    • 17926a79320afa9b95df6b977b40cca6d8713cea and later · before c43ffdcfdbb5567b1f143556df8a04b4eeea041caffected · git
    • before 2.6.22not affected · semver

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Debian:12linuxbefore 6.1.176-16.1.176-1
Debian:13linuxbefore 6.12.85-16.12.85-1
Debian:14linuxbefore 6.19.13-16.19.13-1

Same product

linux: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-31431crypto: algif_aead - Revert to operating out-of-placeKEV
    90Now
  • CVE-2022-0847A flaw was found in the way the "flags" member of the new pipe buffer structure was lacking proper initialization in copy_page_to_iter_pipe KEV
    89Now
  • CVE-2021-22555Heap Out-Of-Bounds Write in Netfilter IP6T_SO_SET_REPLACEKEV
    85Now

Published before and after this one in the same product

  • ← EarlierCVE-2026-31674Apr 25, 2026 · netfilter: ip6t_rt: reject oversized addrnr in rt_mt6_check()
    28Monitor
  • ← EarlierCVE-2026-31675Apr 25, 2026 · net/sched: sch_netem: fix out-of-bounds access in packet corruption
    31Monitor
  • Later →CVE-2026-31677Apr 25, 2026 · crypto: af_alg - limit RX SG extraction by receive buffer budget
    22Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
Linux Linux03fd2ef73cb4ffd0af100a95b634af54f474414eVendor (CNA)
Linux Linux0afdfd4941c1b60a1f5c361760daa970edca60cdVendor (CNA)
Linux Linux29b44d904dceb832be880def08b8cb17a0aba91cVendor (CNA)
Linux Linux6c3a0fbdafef8316e34ae22333e317a341e737cdVendor (CNA)
Linux Linuxa1a8efde03a40b6c658d580e96644d9b9a2a0d3aVendor (CNA)
Linux Linuxa6bcf8010af093fe04f7100562e9542ab7882585Vendor (CNA)
Linux Linuxc43ffdcfdbb5567b1f143556df8a04b4eeea041cVendor (CNA)
Linux Linuxd0035e634dae83237ab7f5681eb52b2f65d0ceb8Vendor (CNA)
azl3 kernel 6.6.134.1-2 on Azure Linux 3.06.6.137.1-1 · CBL-Mariner ReleasesMicrosoft (MSRC)
debian:linux6.1.176-1 · Debian:12Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

No history yet (it accumulates with the daily EPSS job).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • No account or password is required.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
none
Integrity
none
Availability
high · the service can be disrupted
Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality impact
None
Integrity impact
None
Availability impact
High

Weakness class (CWE)

CWE-362 · Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')

CVSS vector

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

nvd-secondary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

ATT&CK techniques

—

Change log

  1. SSVC exploitation— → none
  2. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Show all references (8 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records