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NVD / CVE Program· CNA Linux

CVE-2026-31427: netfilter: nf_conntrack_sip: fix use of uninitialized rtp_addr in process_sdp

Noroxi assessment

Priority: Monitor (action score 22/100)

  • 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: 0.12% (FIRST EPSS).
  • Someone with local access to the system can trigger it. A low-privileged account is enough. No user action is required. No special conditions are required; it is repeatable.
  • Fixed version: Linux Linux 01f34a80ac23ae90b1909b94b4ed05343a62f646, 52fdda318ef2362fc5936385bcb8b3d0328ee629, 6a2b724460cb67caed500c508c2ae5cf012e4db4; azl3 kernel 6.6.130.1-3 on Azure Linux 3.0 6.6.134.1-2.

Low priority for now. Upgrade to Linux Linux 01f34a80ac23ae90b1909b94b4ed05343a62f646, 52fdda318ef2362fc5936385bcb8b3d0328ee629, 6a2b724460cb67caed500c508c2ae5cf012e4db4; azl3 kernel 6.6.130.1-3 on Azure Linux 3.0 6.6.134.1-2 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: fix use of uninitialized rtp_addr in process_sdp process_sdp() declares union nf_inet_addr rtp_addr on the stack and passes it to the nf_nat_sip sdp_session hook after walking the SDP media descriptions. However rtp_addr is only initialized inside the media loop when a recognized media type with a non-zero port is found. If the SDP body contains no m= lines, only inactive media sections (m=audio 0 ...) or only unrecognized media types, rtp_addr is never assigned. Despite that, the function still calls hooks->sdp_session() with &rtp_addr, causing nf_nat_sdp_session() to format the stale stack value as an IP address and rewrite the SDP session owner and connection lines with it. With CONFIG_INIT_STACK_ALL_ZERO (default on most distributions) this results in the session-level o= and c= addresses being rewritten to 0.0.0.0 for inactive SDP sessions. Without stack auto-init the rewritten address is whatever happened to be on the stack. Fix this by pre-initializing rtp_addr from the session-level connection address (caddr) when available, and tracking via a have_rtp_addr flag whether any valid address was established. Skip the sdp_session hook entirely when no valid address exists.

MediumCVSS 5.5 · v3.1—No exploit Fix available
Published
Apr 13, 2026
Updated
Nov 5, 2026
EPSS
0.1% · 1th percentile

Report tools

JSON

Action score

22

Monitor

Low priority for now.

CVSS
22 / 40 · 5.5 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.1%

CISA SSVC decision

Exploitation
none
Automatable
no
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

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.

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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

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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.

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 5.10.253
  • linux linux kernel5.11 and later · before 5.15.203
  • linux linux kernel5.16 and later · before 6.1.168
  • linux linux kernel6.2 and later · before 6.6.131
  • linux linux kernel6.7 and later · before 6.12.80
  • linux linux kernel6.13 and later · before 6.18.21
  • linux linux kernel6.19 and later · before 6.19.11
  • linux linux kernel7.0

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
    • 4ab9e64e5e3c0516577818804aaf13a630d67bc9 and later · before faa6ea32797a1847790514ff0da1be1d09771580affected · git
    • 4ab9e64e5e3c0516577818804aaf13a630d67bc9 and later · before 82baeb871e8f04906bc886273fdf0209e1754eb3affected · git
    • 4ab9e64e5e3c0516577818804aaf13a630d67bc9 and later · before 6e5e3c87b7e6212f1d8414fc2e4d158b01e12025affected · git
    • 4ab9e64e5e3c0516577818804aaf13a630d67bc9 and later · before fe463e76c9b4b0b43b5ee8961b4c500231f1a3f6affected · git
    • 4ab9e64e5e3c0516577818804aaf13a630d67bc9 and later · before 7edca70751b9bdb5b83eed53cde21eccf3c86147affected · git
    • 4ab9e64e5e3c0516577818804aaf13a630d67bc9 and later · before 01f34a80ac23ae90b1909b94b4ed05343a62f646affected · git
    • 4ab9e64e5e3c0516577818804aaf13a630d67bc9 and later · before 52fdda318ef2362fc5936385bcb8b3d0328ee629affected · git
    • 4ab9e64e5e3c0516577818804aaf13a630d67bc9 and later · before 6a2b724460cb67caed500c508c2ae5cf012e4db4affected · 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
Debian:12linuxbefore 6.1.170-16.1.170-1
Debian:13linuxbefore 6.12.85-16.12.85-1
Debian:14linuxbefore 6.19.11-16.19.11-1

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-2026-31424Apr 13, 2026 · netfilter: x_tables: restrict xt_check_match/xt_check_target extensions for NFPROTO_ARP
    22Monitor
  • ← EarlierCVE-2026-31426Apr 13, 2026 · ACPI: EC: clean up handlers on probe failure in acpi_ec_setup()
    28Monitor
  • Later →CVE-2026-31428Apr 13, 2026 · netfilter: nfnetlink_log: fix uninitialized padding leak in NFULA_PAYLOAD
    22Monitor

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 Linux01f34a80ac23ae90b1909b94b4ed05343a62f646Vendor (CNA)
Linux Linux52fdda318ef2362fc5936385bcb8b3d0328ee629Vendor (CNA)
Linux Linux6a2b724460cb67caed500c508c2ae5cf012e4db4Vendor (CNA)
Linux Linux6e5e3c87b7e6212f1d8414fc2e4d158b01e12025Vendor (CNA)
Linux Linux7edca70751b9bdb5b83eed53cde21eccf3c86147Vendor (CNA)
Linux Linux82baeb871e8f04906bc886273fdf0209e1754eb3Vendor (CNA)
Linux Linuxfaa6ea32797a1847790514ff0da1be1d09771580Vendor (CNA)
Linux Linuxfe463e76c9b4b0b43b5ee8961b4c500231f1a3f6Vendor (CNA)
azl3 kernel 6.6.130.1-3 on Azure Linux 3.06.6.134.1-2 · CBL-Mariner ReleasesMicrosoft (MSRC)
debian:linux6.1.170-1 · 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.

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.

  • CVE-2024-50302510 days apartHID: core: zero-initialize the report bufferKEV
    52Plan
  • CVE-2026-5298972 days apartnvmet-tcp: propagate nvmet_tcp_build_pdu_iovec() errors to its callers
    39Monitor
  • CVE-2026-5322573 days apartsctp: fix uninit-value in __sctp_rcv_asconf_lookup()
    36Monitor
  • CVE-2024-47685539 days apartnetfilter: nf_reject_ipv6: fix nf_reject_ip6_tcphdr_put()
    36Monitor
  • CVE-2026-5317073 days apartaccel/ethosu: reject DMA commands with uninitialized length
    35Monitor
  • CVE-2026-4313923 days apartxfrm6: fix uninitialized saddr in xfrm6_get_saddr()
    34Monitor

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

  • Someone with local access to the system can trigger it.
  • A low-privileged account is enough.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
none
Integrity
none
Availability
high · the service can be disrupted
Attack vector
Local
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality impact
None
Integrity impact
None
Availability impact
High

Weakness class (CWE)

CWE-908 · Use of Uninitialized Resource

CVSS vector

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

nvd-primary

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 (10 more)

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

All records