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CVE.org (no NVD analysis yet)· CNA Linux

CVE-2026-99139: tcp: fix use-after-free in do_tcp_getsockopt(TCP_CONGESTION)

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: 0.17% (FIRST EPSS).
  • Fixed version: Linux Linux 08dc5c62c09653d1c4ba67a009beb138486c2604, 4b0930d66dde0a1d1898f0edbbb5496c4dfa5f03, 5271b79b7ad68dcb222e893773f92bdabf7750f3; azl3 kernel 6.6.157.1-1 on Azure Linux 3.0 Release Notes; azl3 kernel 6.6.159.1-1 on Azure Linux 3.0 6.6.161.1-1.
  • Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Low priority for now. Upgrade to Linux Linux 08dc5c62c09653d1c4ba67a009beb138486c2604, 4b0930d66dde0a1d1898f0edbbb5496c4dfa5f03, 5271b79b7ad68dcb222e893773f92bdabf7750f3; azl3 kernel 6.6.157.1-1 on Azure Linux 3.0 Release Notes; azl3 kernel 6.6.159.1-1 on Azure Linux 3.0 6.6.161.1-1 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: tcp: fix use-after-free in do_tcp_getsockopt(TCP_CONGESTION) do_tcp_getsockopt() reads icsk->icsk_ca_ops->name without holding rcu_read_lock(). Since commit 0baf26b0fcd7 ("bpf: tcp: Support tcp_congestion_ops in bpf"), icsk_ca_ops can point to dynamically allocated BPF struct_ops memory that may be freed concurrently via setsockopt(TCP_CONGESTION), leading to a use-after-free. BUG: KASAN: slab-use-after-free in _copy_to_user+0x37/0x60 Read of size 16 at addr ffff888013505260 by task exploit/149 _copy_to_user+0x37/0x60 do_tcp_getsockopt+0x158a/0x2460 (net/ipv4/tcp.c:4585) tcp_getsockopt+0x91/0xf0 __sys_getsockopt+0xf7/0x170 Fix this by holding rcu_read_lock() around the ca_ops->name access, using READ_ONCE() to load icsk_ca_ops, and copying the name to a stack buffer before releasing the lock. Also annotate the relevant icsk_ca_ops stores with WRITE_ONCE() to fix the accompanying KCSAN data-race issue.

—No exploit Fix available
Published
Oct 28, 2026
Updated
Oct 30, 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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  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

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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

    • 5.6affected
    • 0baf26b0fcd74bbfcef53c5d5e8bad2b99c8d0d2 and later · before a60e62705c17534d6b6539de7b3a40c259e6827faffected · git
    • 0baf26b0fcd74bbfcef53c5d5e8bad2b99c8d0d2 and later · before 4b0930d66dde0a1d1898f0edbbb5496c4dfa5f03affected · git
    • 0baf26b0fcd74bbfcef53c5d5e8bad2b99c8d0d2 and later · before 08dc5c62c09653d1c4ba67a009beb138486c2604affected · git
    • 0baf26b0fcd74bbfcef53c5d5e8bad2b99c8d0d2 and later · before c1804ef016392dd91267d2207ee43b1de34302caaffected · git
    • 0baf26b0fcd74bbfcef53c5d5e8bad2b99c8d0d2 and later · before a8e45471afa230c1431c26c8e99ec24377e3b514affected · git
    • 0baf26b0fcd74bbfcef53c5d5e8bad2b99c8d0d2 and later · before 5271b79b7ad68dcb222e893773f92bdabf7750f3affected · git
    • before 5.6not affected · semver
    • 6.1.191 and later · up to and including 6.1.*not affected · semver
    • 6.6.161 and later · up to and including 6.6.*not affected · semver

Package-level exposure

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

EcosystemPackageAffected rangeFix
Debian:12linuxfrom 0—
Debian:13linuxbefore 6.12.115-26.12.115-2

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-2026-99137Oct 28, 2026 · cifs: don't update i_size in cifs_do_truncate without a cached handle
    0Monitor
  • ← EarlierCVE-2026-99138Oct 28, 2026 · tcp: fix use-after-free in do_tcp_getsockopt(TCP_CC_INFO)
    0Monitor
  • Later →CVE-2026-99140Oct 28, 2026 · tracing: Fix hist trigger timestamps for buffered events
    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 Linux08dc5c62c09653d1c4ba67a009beb138486c2604Vendor (CNA)
Linux Linux4b0930d66dde0a1d1898f0edbbb5496c4dfa5f03Vendor (CNA)
Linux Linux5271b79b7ad68dcb222e893773f92bdabf7750f3Vendor (CNA)
Linux Linuxa60e62705c17534d6b6539de7b3a40c259e6827fVendor (CNA)
Linux Linuxa8e45471afa230c1431c26c8e99ec24377e3b514Vendor (CNA)
Linux Linuxc1804ef016392dd91267d2207ee43b1de34302caVendor (CNA)
azl3 kernel 6.6.157.1-1 on Azure Linux 3.0Release NotesMicrosoft (MSRC)
azl3 kernel 6.6.159.1-1 on Azure Linux 3.06.6.161.1-1 · Release NotesMicrosoft (MSRC)
debian:linux6.12.115-2 · Debian:13Package 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.

  1. Published
  2. Fix recordedsame day
  3. TodayNov 7, 2026+10 d
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).

National notice (Türkiye Cybersecurity Directorate / USOM)

Official security notices citing this record; remediation advice is on the agency's page.

All national notices →

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. Exploit maturity— → none
  2. Fix✗ → ✓

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

References

Show all references (5 more)

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

All records