CyberSecBulletin
CVE-2026-52999NVD status: Modified

Linux: Out-of-bounds Read

Published Updated By the CyberSecBulletin desk

CVE-2026-52999 is a critical-severity out-of-bounds read vulnerability in Linux, with a CVSS 3.1 base score of 9.1 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. The record lists versions 0145548346c4a30981a870a8ca00eac46ba27e85, 1c136f2c44a5913646bac85303612fd0825197a0, 1e19a07291bb8682c14c39a64725a3ae54ab8ccc as the first without the flaw, so updating Linux to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.59% chance of exploitation within 30 days, which is low compared with other CVEs.

Patch this week

Critical severity: a successful attack would have severe impact.

What to do

  1. Update Linux to 0145548346c4a30981a870a8ca00eac46ba27e85 or 1c136f2c44a5913646bac85303612fd0825197a0 or 1e19a07291bb8682c14c39a64725a3ae54ab8ccc or 32e50f92c7cf3f4eba29622179a5fcdc2aebab41, whichever matches your release line, or a later version.
  2. Update Linux Kernel to 4.20 or 5.0 or 5.10.258 or 5.15.209, whichever matches your release line, or a later version.
  3. Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.

Affected products and versions

VendorProductAffected versionsFixed in
LinuxLinux1a6a0951fc009f6d9fe8ebea2d2417d80d54097b up to, but not including, 0145548346c4a30981a870a8ca00eac46ba27e85; 1a6a0951fc009f6d9fe8ebea2d2417d80d54097b up to, but not including, 1c136f2c44a5913646bac85303612fd0825197a0; 1a6a0951fc009f6d9fe8ebea2d2417d80d54097b up to, but not including, 1e19a07291bb8682c14c39a64725a3ae54ab8ccc; 1a6a0951fc009f6d9fe8ebea2d2417d80d54097b up to, but not including, 32e50f92c7cf3f4eba29622179a5fcdc2aebab41; 1a6a0951fc009f6d9fe8ebea2d2417d80d54097b up to, but not including, 70a3f31d25cf2ec9d4ddfa408120171ead955623; 1a6a0951fc009f6d9fe8ebea2d2417d80d54097b up to, but not including, 21883587593d7c8bb519a79460a0b5bc5ffbdabd; 1a6a0951fc009f6d9fe8ebea2d2417d80d54097b up to, but not including, edb78a142d2e5948e63647c0646aa7e7886935f0; 1a6a0951fc009f6d9fe8ebea2d2417d80d54097b up to, but not including, f5ca450087c3baf3651055e7a6de92600f827af3; and 5 more ranges0145548346c4a30981a870a8ca00eac46ba27e85, 1c136f2c44a5913646bac85303612fd0825197a0, 1e19a07291bb8682c14c39a64725a3ae54ab8ccc, 32e50f92c7cf3f4eba29622179a5fcdc2aebab41, 70a3f31d25cf2ec9d4ddfa408120171ead955623, 21883587593d7c8bb519a79460a0b5bc5ffbdabd
SiemensSIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AB0)V3.1.6 and later; V3.1.7 and laterNot stated
SiemensSIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AC0)V3.1.6 and later; V3.1.7 and laterNot stated
SiemensSIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AB0)V3.1.6 and later; V3.1.7 and laterNot stated
SiemensSIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AC0)V3.1.6 and later; V3.1.7 and laterNot stated
SiemensSIPLUS S7-1500 CPU 1518-4 PN/DP MFP (6AG1518-4AX00-4AC0)V3.1.6 and later; V3.1.7 and laterNot stated
LinuxLinux Kernel4.19.26 up to, but not including, 4.20; 4.20.13 up to, but not including, 5.0; 5.0.1 up to, but not including, 5.10.258; 5.11 up to, but not including, 5.15.209; 5.16 up to, but not including, 6.1.175; 6.2 up to, but not including, 6.6.141; 6.7 up to, but not including, 6.12.91; 6.13 up to, but not including, 6.18.33; and 2 more ranges4.20, 5.0, 5.10.258, 5.15.209, 6.1.175, 6.6.141

Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
NetworkCan be exploited remotely over a network, including the internet.
Attack complexity
LowNo special conditions are needed; the attack works reliably.
Privileges required
NoneNo account or login is needed.
User interaction
NoneNo action by a victim is required.
Scope
UnchangedImpact stays within the vulnerable component.
Confidentiality
HighAll data handled by the component can be read.
Integrity
NoneNothing can be modified.
Availability
HighThe component can be taken down completely.

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H. Scored by CNA.

Official description

In the Linux kernel, the following vulnerability has been resolved: netfilter: nfnetlink_osf: fix out-of-bounds read on option matching In nf_osf_match(), the nf_osf_hdr_ctx structure is initialized once and passed by reference to nf_osf_match_one() for each fingerprint checked. During TCP option parsing, nf_osf_match_one() advances the shared ctx->optp pointer. If a fingerprint perfectly matches, the function returns early without restoring ctx->optp to its initial state. If the user has configured NF_OSF_LOGLEVEL_ALL, the loop continues to the next fingerprint. However, because ctx->optp was not restored, the next call to nf_osf_match_one() starts parsing from the end of the options buffer. This causes subsequent matches to read garbage data and fail immediately, making it impossible to log more than one match or logging incorrect matches. Instead of using a shared ctx->optp pointer, pass the context as a constant pointer and use a local pointer (optp) for TCP option traversal. This makes nf_osf_match_one() strictly stateless from the caller's perspective, ensuring every fingerprint check starts at the correct option offset.

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Out-of-bounds Read

The product reads data past the end, or before the beginning, of the intended buffer.

How developers prevent this class of flaw

  • Use a language that provides appropriate memory abstractions.

More Out-of-bounds Read vulnerabilities (CWE-125)

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: none, automatable: yes, technical impact: partial).
  3. Record last changed materially (score, affected products, status or references).

References

Recent Out-of-bounds Read vulnerabilities

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