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NVD / CVE Program· CNA Linux

CVE-2026-72251: netfilter: nf_nat_sip: reload possible stale data pointer

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: 0.71% (FIRST EPSS); higher than 53.9% 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 0e76e3e886cc9ee027337d5ad39cb96f57b7bdc7, 2bcf2c5052fb5e73e255140ab43f056aef409c27, 57e4e29644ec054d7021d296407e7ddd844afea2.

Low priority for now. Upgrade to Linux Linux 0e76e3e886cc9ee027337d5ad39cb96f57b7bdc7, 2bcf2c5052fb5e73e255140ab43f056aef409c27, 57e4e29644ec054d7021d296407e7ddd844afea2 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_nat_sip: reload possible stale data pointer quoting sashiko: ------------------------------------------------------------------------ [..] noticed a potential memory bug and header corruption involving the SIP NAT helper. In net/netfilter/nf_nat_sip.c:nf_nat_sip(): if (skb_ensure_writable(skb, skb->len)) { nf_ct_helper_log(skb, ct, "cannot mangle packet"); return NF_DROP; } uh = (void *)skb->data + protoff; uh->dest = ct_sip_info->forced_dport; if (!nf_nat_mangle_udp_packet(skb, ct, ctinfo, protoff, 0, 0, NULL, 0)) { If a cloned or fragmented SKB is reallocated by skb_ensure_writable(), the old data buffer is freed. However, nf_nat_sip() fails to update *dptr to point to the new buffer. It also appears to use nf_nat_mangle_udp_packet() on what could be a TCP packet, which would overwrite the sequence number with a checksum update. ------------------------------------------------------------------------ nf_conntrack_sip linerizes skbs, hence no fragmented skb can be seen. But clones are possible, so rebuild dptr. Disable nf_nat_mangle_udp_packet() branch for TCP streams. It doesn't look like this can ever happen, else we should have received bug reports about this, so just check the conntrack is UDP and drop otherwise. The calling conntrack_sip set ->forced_dport for SIP_HDR_VIA_UDP messages, so I don't think this is ever expected to be true for a TCP stream.

CriticalCVSS 9.8 · v3.1—No exploit Fix available
Published
Aug 15, 2026
Updated
Oct 16, 2026
EPSS
0.7% · 53th percentile
CWE
—

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 · 0.7%

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.

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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?

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.

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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

    • 3.9affected
    • 7266507d89991fa1e989283e4e032c6d9357fe26 and later · before bded21a4bf9bf86a79148be735723a97ca9a7532affected · git
    • 7266507d89991fa1e989283e4e032c6d9357fe26 and later · before dc11f26685aa850f237226f0f463647aea58ab7caffected · git
    • 7266507d89991fa1e989283e4e032c6d9357fe26 and later · before e38143c9b477f2968024c47c647dd4456a40aff1affected · git
    • 7266507d89991fa1e989283e4e032c6d9357fe26 and later · before 57e4e29644ec054d7021d296407e7ddd844afea2affected · git
    • 7266507d89991fa1e989283e4e032c6d9357fe26 and later · before eae9c6ccb5af69c713a65f8ae219f5c1aa32cd17affected · git
    • 7266507d89991fa1e989283e4e032c6d9357fe26 and later · before 2bcf2c5052fb5e73e255140ab43f056aef409c27affected · git
    • 7266507d89991fa1e989283e4e032c6d9357fe26 and later · before 0e76e3e886cc9ee027337d5ad39cb96f57b7bdc7affected · git
    • 7266507d89991fa1e989283e4e032c6d9357fe26 and later · before 77e43bcb7ec177e293a5c3f1b91a2c5aebfb6c68affected · git
    • before 3.9not affected · semver

Package-level exposure

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

EcosystemPackageAffected rangeFix
Debian:12linuxbefore 6.1.180-16.1.180-1
Debian:13linuxbefore 6.12.100-16.12.100-1
Debian:14linuxbefore 7.1.5-17.1.5-1

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-2026-72247Aug 15, 2026 · netfilter: nf_conncount: fix zone comparison in tuple dedup
    30Monitor
  • ← EarlierCVE-2026-72250Aug 15, 2026 · netfilter: nf_conntrack_reasm: guard mac_header adjustment after IPv6 defrag
    31Monitor
  • Later →CVE-2026-72252Aug 15, 2026 · netfilter: nft_set_pipapo: don't leak bad clone into future transaction
    31Monitor

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 Linux0e76e3e886cc9ee027337d5ad39cb96f57b7bdc7Vendor (CNA)
Linux Linux2bcf2c5052fb5e73e255140ab43f056aef409c27Vendor (CNA)
Linux Linux57e4e29644ec054d7021d296407e7ddd844afea2Vendor (CNA)
Linux Linux77e43bcb7ec177e293a5c3f1b91a2c5aebfb6c68Vendor (CNA)
Linux Linuxbded21a4bf9bf86a79148be735723a97ca9a7532Vendor (CNA)
Linux Linuxdc11f26685aa850f237226f0f463647aea58ab7cVendor (CNA)
Linux Linuxe38143c9b477f2968024c47c647dd4456a40aff1Vendor (CNA)
Linux Linuxeae9c6ccb5af69c713a65f8ae219f5c1aa32cd17Vendor (CNA)
debian:linux6.1.180-1 · 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

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)

—

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 (7 more)

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

All records