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Vulnerabilities

Vulnerability · CVE-2026-52986

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(),…

Published Jun 24, 2026 · catalog updated Oct 15, 2026 · linux kernel

Check if you run it

No confirmed exploitation is on record for CVE-2026-52986. EPSS is 0.63%. Act only if a listed version of linux kernel is installed.

Gaps on this record

  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
Critical9.8
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.63%
Remediation
Advisory link
Affected products
cpe linux/linux kernel

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 .

Are you affected?

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  • cpe linux/linux kernel7.1

How to fix CVE-2026-52986

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-52986. EPSS is 0.63%. Act only if a listed version of linux kernel is installed.

Which versions are affected?

Compare what you have installed with linux/linux kernel 7.1. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-476: NULL Pointer Dereference. EPSS 0.63%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Technology hubs

Ubuntu security

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. Jun 24, 2026 · NIST NVD

    Detected

    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 c

  2. Oct 15, 2026 · NIST NVD

    Updated

    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 c

Sources

  • CVE.orgVulnerability recordCVE-2026-52986

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2026-52986

    30-day exploitation probability 0.6%

    first.org
  • NIST NVDVulnerability recordCVE-2026-52986

    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 di

    nvd.nist.gov
  • Ubuntu Security NoticesVendor advisoryCVE-2026-52986

    Several security issues were discovered in the Linux kernel. An attacker could possibly use these to compromise the system. This update corrects flaws in the following subsystems: - Hardware crypto device drivers; - NVIDIA Tegra memory controller driver; - Network drivers; - USB

    ubuntu.com

References

Freshness

Last verified in this catalog Oct 18, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.