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

CVE-2026-99138: tcp: fix use-after-free in do_tcp_getsockopt(TCP_CC_INFO)

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 385e474086c2e7e29e2dded690be40dc273e20ee, 39aa489e85752f9de214edb0f85e4d578e57af29, 66b831b427301a9c3e485564009d476631413103; 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 Release Notes.
  • Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Low priority for now. Upgrade to Linux Linux 385e474086c2e7e29e2dded690be40dc273e20ee, 39aa489e85752f9de214edb0f85e4d578e57af29, 66b831b427301a9c3e485564009d476631413103; 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 Release Notes 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_CC_INFO) do_tcp_getsockopt() reads icsk->icsk_ca_ops and dereferences the get_info function pointer without rcu_read_lock(). With BPF struct_ops congestion control, ca_ops can point to dynamically allocated memory that is freed concurrently, resulting in a use-after-free when the kernel dereferences or calls through the stale pointer. BUG: KASAN: slab-use-after-free in do_tcp_getsockopt+0x2037/0x23e0 Read of size 8 at addr ffff888013701258 by task exploit/149 do_tcp_getsockopt+0x2037/0x23e0 (net/ipv4/tcp.c:4564) tcp_getsockopt+0x91/0xf0 __sys_getsockopt+0xf7/0x170 Fix this by wrapping the ca_ops load and get_info call within rcu_read_lock()/rcu_read_unlock(), and using READ_ONCE() to load the icsk_ca_ops pointer.

—No exploit Fix available
Published
Oct 28, 2026
Updated
Oct 30, 2026
EPSS
0.1% · 7th 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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  • 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 7c312f17917455eedcea29735fa302ebb93cb9b9affected · git
    • 0baf26b0fcd74bbfcef53c5d5e8bad2b99c8d0d2 and later · before 66b831b427301a9c3e485564009d476631413103affected · git
    • 0baf26b0fcd74bbfcef53c5d5e8bad2b99c8d0d2 and later · before a8b024cbf62b497062c86995737fc303e4cc384eaffected · git
    • 0baf26b0fcd74bbfcef53c5d5e8bad2b99c8d0d2 and later · before 8d5fc9e6dc09174d0da6e59678eb8e01a890cbd3affected · git
    • 0baf26b0fcd74bbfcef53c5d5e8bad2b99c8d0d2 and later · before e057d201640eebb8ed47ec924872c41570a3bd28affected · git
    • 0baf26b0fcd74bbfcef53c5d5e8bad2b99c8d0d2 and later · before 86814e5370068ec2bf0caa6e6d55c3e5bfc6c324affected · git
    • 0baf26b0fcd74bbfcef53c5d5e8bad2b99c8d0d2 and later · before 39aa489e85752f9de214edb0f85e4d578e57af29affected · git
    • 0baf26b0fcd74bbfcef53c5d5e8bad2b99c8d0d2 and later · before 385e474086c2e7e29e2dded690be40dc273e20eeaffected · git
    • before 5.6not 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-2026-99136Oct 28, 2026 · dm-crypt: fix a tiny race condition in crypt_dec_pending
    28Monitor
  • ← EarlierCVE-2026-99137Oct 28, 2026 · cifs: don't update i_size in cifs_do_truncate without a cached handle
    0Monitor
  • Later →CVE-2026-99139Oct 28, 2026 · tcp: fix use-after-free in do_tcp_getsockopt(TCP_CONGESTION)
    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 Linux385e474086c2e7e29e2dded690be40dc273e20eeVendor (CNA)
Linux Linux39aa489e85752f9de214edb0f85e4d578e57af29Vendor (CNA)
Linux Linux66b831b427301a9c3e485564009d476631413103Vendor (CNA)
Linux Linux7c312f17917455eedcea29735fa302ebb93cb9b9Vendor (CNA)
Linux Linux86814e5370068ec2bf0caa6e6d55c3e5bfc6c324Vendor (CNA)
Linux Linux8d5fc9e6dc09174d0da6e59678eb8e01a890cbd3Vendor (CNA)
Linux Linuxa8b024cbf62b497062c86995737fc303e4cc384eVendor (CNA)
Linux Linuxe057d201640eebb8ed47ec924872c41570a3bd28Vendor (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 3.0Release 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 5, 2026+8 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 (7 more)

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

All records