VulnerabilityPublished 23 Oct 2026Updated 24 Oct 2026

CVE-2026-98952: Linux kernel · pfcp: make sure the SEID is linear before reading it

Affects Linux kernelSource CVE Database V5

Not known to be exploited · CVSS 7.3 High · fixed in b18a6496495495e2dc27e525aa3315a0c59b9513 : patch Linux kernel soon.

Data as of 26 Oct 2026, 17:30 UTC

CVSS 3.1 base score

7.3High

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.3% chance of exploitation in 30 days – higher than 31% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in b18a6496495495e2dc27e525aa3315a0c59b9513, 23609bce9e1de525d1d0e73fc68c6e7971d0b49e, 3192a5e398c64d48aad64a09e29643e327369bc4 +1

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

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: None
Scope: Unchanged
Confidentiality: Low
Integrity: Low
Availability: Low

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: Low: There is some loss of confidentiality. Access to some restricted information is obtained, but the attacker does not have control over what information is obtained, or the amount or kind of loss is limited. The information disclosure does not cause a direct, serious loss to the impacted component.
Integrity: Low: Modification of data is possible, but the attacker does not have control over the consequence of a modification, or the amount of modification is limited. The data modification does not have a direct, serious impact on the impacted component.
Availability: Low: Performance is reduced or there are interruptions in resource availability. Even if repeated exploitation of the vulnerability is possible, the attacker does not have the ability to completely deny service to legitimate users. The resources in the impacted component are either partially available all of the time, or fully available only some of the time, but overall there is no direct, serious consequence to the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 23 Oct 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade Linux kernel to b18a6496495495e2dc27e525aa3315a0c59b9513, 23609bce9e1de525d1d0e73fc68c6e7971d0b49e, 3192a5e398c64d48aad64a09e29643e327369bc4 or 2fb6d05f706d79bbdc88835be2f4f45ab56dd819.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected ≥ 6dd514f48110ebb4bf36875b9e7e02d07b589caa, < b18a6496495495e2dc27e525aa3315a0c59b9513	Fixed in b18a6496495495e2dc27e525aa3315a0c59b9513
LinuxLinux	Affected ≥ 6dd514f48110ebb4bf36875b9e7e02d07b589caa, < 23609bce9e1de525d1d0e73fc68c6e7971d0b49e	Fixed in 23609bce9e1de525d1d0e73fc68c6e7971d0b49e
LinuxLinux	Affected ≥ 6dd514f48110ebb4bf36875b9e7e02d07b589caa, < 3192a5e398c64d48aad64a09e29643e327369bc4	Fixed in 3192a5e398c64d48aad64a09e29643e327369bc4
LinuxLinux	Affected ≥ 6dd514f48110ebb4bf36875b9e7e02d07b589caa, < 2fb6d05f706d79bbdc88835be2f4f45ab56dd819	Fixed in 2fb6d05f706d79bbdc88835be2f4f45ab56dd819
LinuxLinux	Affected =6.10	Fixed in–

AI-suggested

This vulnerability has been fixed in the Linux kernel. Users should update to the fixed versions identified by the commits (hashes provided). There is no indication that additional mitigation steps are required beyond applying the official patch.

Description

CVE-2026-98952 is a vulnerability in the Linux kernel's PFCP packet processing code where the SEID field is not properly checked for linearity before being read. This can cause out-of-bounds reads when processing short or fragmented PFCP packets with the S flag set. The issue has been fixed by ensuring the entire SEID is pulled into the linear area before access and dropping packets that are too short.

Impact

An attacker can send crafted PFCP packets that cause the kernel to read beyond the end of packet data, potentially leading to incorrect tunnel metadata classification. The CVSS score of 7.3 indicates a high severity with impacts on confidentiality, integrity, and availability. There is no indication of known exploitation in the wild.

Summary

The vulnerability exists in the Linux kernel's pfcp_session_recv() function, which reads an 8-byte SEID field following the PFCP header without verifying that this data is fully linear in the skb buffer. While pfcp_encap_recv() ensures the UDP and PFCP headers are linear, it does not cover the SEID when the S flag is set. This can lead to reading beyond the packet data boundary, causing the kernel to store invalid data in tunnel metadata used later for classification. The fix involves using pskb_may_pull() to pull the entire SEID into the linear area before reading it and dropping packets that are too short. Additionally, offsetofend() is used instead of sizeof(struct pfcphdr_session) to correctly handle header size due to structure alignment differences.

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 26 Oct 2026, 09:43 UTC

Technical details

References

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