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NVD / CVE Program· CNA Linux

CVE-2026-80849: net/tcp-ao: fix use-after-free of current_key on reconnect to another peer

Noroxi assessment

Priority: Monitor (action score 0/100)

  • 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: 0.16% (FIRST EPSS).
  • Fixed version: Linux Linux 2857dcbd03cf3354af0fba1b65c6a260fb43811a, 73fde8fe4469f4ed8f0afcc0b9d6413002a9e6b3, 84a93b4e012587d0a4a84ffb23ec6da18e9d85f9.

Low priority for now. Upgrade to Linux Linux 2857dcbd03cf3354af0fba1b65c6a260fb43811a, 73fde8fe4469f4ed8f0afcc0b9d6413002a9e6b3, 84a93b4e012587d0a4a84ffb23ec6da18e9d85f9 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: net/tcp-ao: fix use-after-free of current_key on reconnect to another peer tcp_inbound_ao_hash() is called before bh_lock_sock_nested() is taken, with only rcu_read_lock() held. On the fast path for established sockets, if the rnext_keyid sent by the peer differs from current_key->sndid, the key the peer asked for is looked up and stored in current_key. The lookup is inside the RCU read side, but current_key outlives it. When the socket is disconnected and connect() is called again for another peer, tcp_ao_connect_init() unlinks every key that does not match the new peer and frees it with call_rcu(). If current_key points at such a key, it is cleared to NULL. The fast path reads sk_state only once on entry, so a softirq that got into it while the socket was still established can update current_key after that loop has already run. The update is inside the RCU read side, so it comes before the call_rcu() callback, and once the callback frees the key, current_key is left pointing at freed memory. The next transmission picks that pointer up in tcp_get_current_key(). tcp_ao_transmit_skb() then reads the traffic key from the freed object, which is the use-after-free. Wait for one grace period before unlinking, and only if a key is going to be removed. By the time tcp_connect() runs the socket is already in TCP_SYN_SENT, and TCP_AO_ESTABLISHED does not contain TCPF_SYN_SENT, so a softirq entering after the wait cannot reach the fast path, and the ones already in it have finished. The existing NULL handling in the loop is then enough.

—No exploit Fix available
Published
Sep 4, 2026
Updated
Oct 19, 2026
EPSS
0.1% · 6th percentile
CWE
—

Report tools

JSON

Action score

0

Monitor

Low priority for now.

CVSS
0 / 40 · —
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.1%

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Noroxi analysis

What does it mean in your environment?

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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.

—

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

    • 6.7affected
    • 0a3a809089eb1d4a0a2fd0c16b520d603988c859 and later · before 84a93b4e012587d0a4a84ffb23ec6da18e9d85f9affected · git
    • 0a3a809089eb1d4a0a2fd0c16b520d603988c859 and later · before 73fde8fe4469f4ed8f0afcc0b9d6413002a9e6b3affected · git
    • 0a3a809089eb1d4a0a2fd0c16b520d603988c859 and later · before e54ad693eddb40c595add013f545354c538e325baffected · git
    • 0a3a809089eb1d4a0a2fd0c16b520d603988c859 and later · before 2857dcbd03cf3354af0fba1b65c6a260fb43811aaffected · git
    • 0a3a809089eb1d4a0a2fd0c16b520d603988c859 and later · before da4471557f279d0f56605158a625bb6e49ef7d41affected · git
    • before 6.7not affected · semver
    • 6.12.108 and later · up to and including 6.12.*not affected · semver
    • 6.18.49 and later · up to and including 6.18.*not affected · semver
    • 7.1.13 and later · up to and including 7.1.*not affected · semver

Package-level exposure

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

EcosystemPackageAffected rangeFix
Debian:12linux-6.12before 6.12.111-1~deb12u16.12.111-1~deb12u1
Debian:13linuxbefore 6.12.111-16.12.111-1
Debian:14linuxbefore 7.1.13-17.1.13-1

Same product

linux: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-74705udp: fix potential use-after-free in tunnel segmentation
    40Plan
  • CVE-2026-74612veth: fix skb length accounting after XDP frag adjustment
    40Plan
  • CVE-2026-74475vxlan: use neigh_ha_snapshot() in route_shortcircuit()
    40Plan

Published before and after this one in the same product

  • ← EarlierCVE-2026-80847Sep 4, 2026 · tcp: clamp route advmss to TCP_MIN_MSS
    0Monitor
  • ← EarlierCVE-2026-80848Sep 4, 2026 · xfrm: espintcp: fix UAF during close
    0Monitor
  • Later →CVE-2026-80850Sep 4, 2026 · tcp: fix AO info use-after-free in tcp_ao_connect_init()
    0Monitor

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 Linux2857dcbd03cf3354af0fba1b65c6a260fb43811aVendor (CNA)
Linux Linux73fde8fe4469f4ed8f0afcc0b9d6413002a9e6b3Vendor (CNA)
Linux Linux84a93b4e012587d0a4a84ffb23ec6da18e9d85f9Vendor (CNA)
Linux Linuxda4471557f279d0f56605158a625bb6e49ef7d41Vendor (CNA)
Linux Linuxe54ad693eddb40c595add013f545354c538e325bVendor (CNA)
debian:linux6.12.111-1 · Debian:13Package registry (OSV)
debian:linux-6.126.12.111-1~deb12u1 · 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.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

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

No CVSS vector for this record, so attack conditions can't be derived.

Weakness class (CWE)

—

Attack context

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

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Change log

  1. Fix✗ → ✓

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References

Show all references (4 more)

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

All records