Skip to content
Noroxi
NVD / CVE Program· CNA Linux

CVE-2026-52986: netfilter: nf_conntrack_sip: don't use simple_strtoul

Noroxi assessment

Priority: Monitor (action score 39/100)

  • 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: 0.63% (FIRST EPSS); higher than 50.7% of all records.
  • 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 523762e3b6933fff81f01dfa3c60c0774044cdab, 7df9863bf538a626e8a684e59cb2c43eac0ef3c8, 8cd0358379570003659186706e077929d6930c40; azl3 kernel 6.6.139.1-1 on Azure Linux 3.0 6.6.143.1-1.
  • Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Low priority for now. Upgrade to Linux Linux 523762e3b6933fff81f01dfa3c60c0774044cdab, 7df9863bf538a626e8a684e59cb2c43eac0ef3c8, 8cd0358379570003659186706e077929d6930c40; azl3 kernel 6.6.139.1-1 on Azure Linux 3.0 6.6.143.1-1 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: netfilter: nf_conntrack_sip: don't use simple_strtoul Replace unsafe port parsing in epaddr_len(), ct_sip_parse_header_uri(), and ct_sip_parse_request() with a new sip_parse_port() helper that validates each digit against the buffer limit, eliminating the use of simple_strtoul() which assumes NUL-terminated strings. The previous code dereferenced pointers without bounds checks after sip_parse_addr() and relied on simple_strtoul() on non-NUL-terminated skb data. A port that reaches the buffer limit without a trailing character is also rejected as malformed. Also get rid of all simple_strtoul() usage in conntrack, prefer a stricter version instead. There are intentional changes: - Bail out if number is > UINT_MAX and indicate a failure, same for too long sequences. While we do accept 05535 as port 5535, we will not accept e.g. 'sip:10.0.0.1:005060'. While its syntactically valid under RFC 3261, we should restrict this to not waste cycles when presented with malformed packets with 64k '0' characters. - Force base 10 in ct_sip_parse_numerical_param(). This is used to fetch 'expire=' and 'rports='; both are expected to use base-10. - In nf_nat_sip.c, only accept the parsed value if its within the 1k-64k range. - epaddr_len now returns 0 if the port is invalid, as it already does for invalid ip addresses. This is intentional. nf_conntrack_sip performs lots of guesswork to find the right parts of the message to parse. Being stricter could break existing setups. Connection tracking helpers are designed to allow traffic to pass, not to block it. Based on an earlier patch from Jenny Guanni Qu <qguanni@gmail.com>.

CriticalCVSS 9.8 · v3.1—No exploit Fix available
Published
Jun 24, 2026
Updated
Nov 10, 2026
EPSS
0.6% · 50th percentile

Report tools

JSON

Action score

39

Monitor

Low priority for now.

CVSS
39 / 40 · 9.8 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.6%

CISA SSVC decision

Exploitation
none
Automatable
yes
Technical impact
total

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
—
CNA · Linux
9.8
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-2026-52986

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

One daily email digest (06:00 UTC); connect a webhook for KEV listings and weaponized exploits instantly.

Your free account also gets you

  • Stack alerts: add the products and versions you run, get the new CVEs that affect them
  • Uptime monitoring: 1 site, instant email when it goes down
  • Add your domain: subdomains and takeover risk scanned every week (1 domain)
  • 10 scans an hour on the security tools (3 a day without an account), an API key and MCP
  • All your scans in one panel: findings, what changed in the last scan, a report per domain or per client (PDF, share link)
All free tools

Sign up with email · Have an account? Sign in

Free account, no card. Unfollow any time.

Don't want an account? Get "Exploited this week" by email every MondayDon't want an account? RSS feed for linux records
Is your version affected? Check it

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.

We use this product, ask for help

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 kernel2.6.26 and later · before 5.10.258
  • linux linux kernel5.11 and later · before 5.15.209
  • linux linux kernel5.16 and later · before 6.1.175
  • linux linux kernel6.2 and later · before 6.6.141
  • linux linux kernel6.7 and later · before 6.12.91
  • linux linux kernel6.13 and later · before 6.18.33
  • linux linux kernel6.19 and later · before 7.0.10
  • linux linux kernel7.1

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

    • 2.6.26affected
    • 05e3ced297fe755093140e7487e292fb7603316e and later · before 8cd0358379570003659186706e077929d6930c40affected · git
    • 05e3ced297fe755093140e7487e292fb7603316e and later · before 9c6afcb1c3cbb2c0da65b8515ac14d7273872f84affected · git
    • 05e3ced297fe755093140e7487e292fb7603316e and later · before b3264c977e79d8a25778d4fd11520f00fea1329caffected · git
    • 05e3ced297fe755093140e7487e292fb7603316e and later · before ea2ecd29b8f4433e52607192ca91084f95787ca0affected · git
    • 05e3ced297fe755093140e7487e292fb7603316e and later · before 9f69c323ae0ab517e595c2cc74e0ae0d9d085611affected · git
    • 05e3ced297fe755093140e7487e292fb7603316e and later · before 7df9863bf538a626e8a684e59cb2c43eac0ef3c8affected · git
    • 05e3ced297fe755093140e7487e292fb7603316e and later · before 523762e3b6933fff81f01dfa3c60c0774044cdabaffected · git
    • 05e3ced297fe755093140e7487e292fb7603316e and later · before 8cf6809cddcbe301aedfc6b51bcd4944d45795f6affected · git
    • before 2.6.26not affected · semver

Package-level exposure

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

EcosystemPackageAffected rangeFix
AlmaLinux:8bpftoolbefore 4.18.0-553.162.1.el8_104.18.0-553.162.1.el8_10
AlmaLinux:8kernelbefore 4.18.0-553.162.1.el8_104.18.0-553.162.1.el8_10
AlmaLinux:8kernel-abi-stablelistsbefore 4.18.0-553.162.1.el8_104.18.0-553.162.1.el8_10
AlmaLinux:8kernel-corebefore 4.18.0-553.162.1.el8_104.18.0-553.162.1.el8_10
AlmaLinux:8kernel-cross-headersbefore 4.18.0-553.162.1.el8_104.18.0-553.162.1.el8_10
AlmaLinux:8kernel-debugbefore 4.18.0-553.162.1.el8_104.18.0-553.162.1.el8_10
AlmaLinux:8kernel-debug-corebefore 4.18.0-553.162.1.el8_104.18.0-553.162.1.el8_10
AlmaLinux:8kernel-debug-develbefore 4.18.0-553.162.1.el8_104.18.0-553.162.1.el8_10
AlmaLinux:8kernel-debug-modulesbefore 4.18.0-553.162.1.el8_104.18.0-553.162.1.el8_10
AlmaLinux:8kernel-debug-modules-extrabefore 4.18.0-553.162.1.el8_104.18.0-553.162.1.el8_10
AlmaLinux:8kernel-develbefore 4.18.0-553.162.1.el8_104.18.0-553.162.1.el8_10
AlmaLinux:8kernel-docbefore 4.18.0-553.162.1.el8_104.18.0-553.162.1.el8_10
AlmaLinux:8kernel-headersbefore 4.18.0-553.162.1.el8_104.18.0-553.162.1.el8_10
AlmaLinux:8kernel-modulesbefore 4.18.0-553.162.1.el8_104.18.0-553.162.1.el8_10
AlmaLinux:8kernel-modules-extrabefore 4.18.0-553.162.1.el8_104.18.0-553.162.1.el8_10
AlmaLinux:8kernel-rtbefore 4.18.0-553.162.1.rt7.503.el8_104.18.0-553.162.1.rt7.503.el8_10
AlmaLinux:8kernel-rt-corebefore 4.18.0-553.162.1.rt7.503.el8_104.18.0-553.162.1.rt7.503.el8_10
AlmaLinux:8kernel-rt-debugbefore 4.18.0-553.162.1.rt7.503.el8_104.18.0-553.162.1.rt7.503.el8_10
AlmaLinux:8kernel-rt-debug-corebefore 4.18.0-553.162.1.rt7.503.el8_104.18.0-553.162.1.rt7.503.el8_10
AlmaLinux:8kernel-rt-debug-develbefore 4.18.0-553.162.1.rt7.503.el8_104.18.0-553.162.1.rt7.503.el8_10
AlmaLinux:8kernel-rt-debug-modulesbefore 4.18.0-553.162.1.rt7.503.el8_104.18.0-553.162.1.rt7.503.el8_10
AlmaLinux:8kernel-rt-debug-modules-extrabefore 4.18.0-553.162.1.rt7.503.el8_104.18.0-553.162.1.rt7.503.el8_10
AlmaLinux:8kernel-rt-develbefore 4.18.0-553.162.1.rt7.503.el8_104.18.0-553.162.1.rt7.503.el8_10
AlmaLinux:8kernel-rt-modulesbefore 4.18.0-553.162.1.rt7.503.el8_104.18.0-553.162.1.rt7.503.el8_10

+96

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-2026-52984Jun 24, 2026 · net/sched: netem: fix queue limit check to include reordered packets
    22Monitor
  • ← EarlierCVE-2026-52985Jun 24, 2026 · netdevsim: zero initialize struct iphdr in dummy sk_buff
    22Monitor
  • Later →CVE-2026-52988Jun 24, 2026 · netfilter: nf_tables: join hook list via splice_list_rcu() in commit phase
    28Monitor

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 Linux523762e3b6933fff81f01dfa3c60c0774044cdabVendor (CNA)
Linux Linux7df9863bf538a626e8a684e59cb2c43eac0ef3c8Vendor (CNA)
Linux Linux8cd0358379570003659186706e077929d6930c40Vendor (CNA)
Linux Linux8cf6809cddcbe301aedfc6b51bcd4944d45795f6Vendor (CNA)
Linux Linux9c6afcb1c3cbb2c0da65b8515ac14d7273872f84Vendor (CNA)
Linux Linux9f69c323ae0ab517e595c2cc74e0ae0d9d085611Vendor (CNA)
Linux Linuxb3264c977e79d8a25778d4fd11520f00fea1329cVendor (CNA)
Linux Linuxea2ecd29b8f4433e52607192ca91084f95787ca0Vendor (CNA)
azl3 kernel 6.6.139.1-1 on Azure Linux 3.06.6.143.1-1 · CBL-Mariner ReleasesMicrosoft (MSRC)
almalinux:bpftool4.18.0-553.162.1.el8_10 · AlmaLinux:8Package registry (OSV)
almalinux:kernel4.18.0-553.162.1.el8_10 · AlmaLinux:8Package registry (OSV)
almalinux:kernel-rt4.18.0-553.162.1.rt7.503.el8_10 · AlmaLinux:8Package registry (OSV)
almalinux:kernel-rt-core4.18.0-553.162.1.rt7.503.el8_10 · AlmaLinux:8Package registry (OSV)
almalinux:kernel-rt-debug4.18.0-553.162.1.rt7.503.el8_10 · AlmaLinux:8Package registry (OSV)
almalinux:kernel-rt-debug-core4.18.0-553.162.1.rt7.503.el8_10 · AlmaLinux:8Package registry (OSV)
almalinux:kernel-rt-debug-devel4.18.0-553.162.1.rt7.503.el8_10 · AlmaLinux:8Package registry (OSV)
almalinux:kernel-rt-debug-modules4.18.0-553.162.1.rt7.503.el8_10 · AlmaLinux:8Package registry (OSV)
almalinux:kernel-rt-debug-modules-extra4.18.0-553.162.1.rt7.503.el8_10 · AlmaLinux:8Package registry (OSV)
almalinux:kernel-rt-devel4.18.0-553.162.1.rt7.503.el8_10 · AlmaLinux:8Package registry (OSV)
almalinux:kernel-rt-modules4.18.0-553.162.1.rt7.503.el8_10 · AlmaLinux:8Package registry (OSV)
almalinux:kernel-rt-modules-extra4.18.0-553.162.1.rt7.503.el8_10 · AlmaLinux:8Package registry (OSV)
debian:linux6.1.176-1 · Debian:12Package registry (OSV)
red hat:kernel-rt0:4.18.0-553.162.1.rt7.503.el8_10 · Red Hat:enterprise_linux:8::nfvPackage registry (OSV)
red hat:kernel-rt-core0:4.18.0-553.162.1.rt7.503.el8_10 · Red Hat:enterprise_linux:8::nfvPackage registry (OSV)
red hat:kernel-rt-debug0:4.18.0-553.162.1.rt7.503.el8_10 · Red Hat:enterprise_linux:8::nfvPackage registry (OSV)
red hat:kernel-rt-debug-core0:4.18.0-553.162.1.rt7.503.el8_10 · Red Hat:enterprise_linux:8::nfvPackage registry (OSV)
red hat:kernel-rt-debug-debuginfo0:4.18.0-553.162.1.rt7.503.el8_10 · Red Hat:enterprise_linux:8::nfvPackage registry (OSV)
red hat:kernel-rt-debug-devel0:4.18.0-553.162.1.rt7.503.el8_10 · Red Hat:enterprise_linux:8::nfvPackage registry (OSV)
red hat:kernel-rt-debug-kvm0:4.18.0-553.162.1.rt7.503.el8_10 · Red Hat:enterprise_linux:8::nfvPackage registry (OSV)
red hat:kernel-rt-debug-modules0:4.18.0-553.162.1.rt7.503.el8_10 · Red Hat:enterprise_linux:8::nfvPackage registry (OSV)

+13

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).

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

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

Weakness class (CWE)

CWE-476 · NULL Pointer Dereference

CVSS vector

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

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

Change log

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

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

References

Show all references (9 more)

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

All records