CyberSecBulletin
CVE-2026-68335NVD status: Received

Linux: Use After Free

Published Updated By the CyberSecBulletin desk

CVE-2026-68335 is a high-severity use after free vulnerability in Linux, with a CVSS 3.1 base score of 7.8 out of 10. It can be exploited with local access to the system by an attacker with a low-privileged account, without any action from a user. The record lists versions 742ff6f02545212e991cd8b45011e40d2c2ef25a, abff41fd928328bbf3dda1140beb2e61fa424ccd, 03c574112e5d066df0ddce36d7438e850bcf3050 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 0.14% chance of exploitation within 30 days, which is low compared with other CVEs.

Next patch cycle

High severity with no evidence of exploitation so far.

What to do

  1. Update Linux to 742ff6f02545212e991cd8b45011e40d2c2ef25a or abff41fd928328bbf3dda1140beb2e61fa424ccd or 03c574112e5d066df0ddce36d7438e850bcf3050 or 1e2e2d9806944fe485824d617c8b7c78116c22db, whichever matches your release line, or a later version.

Affected products and versions

VendorProductAffected versionsFixed in
LinuxLinuxc809195f5523dd4d09403bbb1c9732d548aa0d1e up to, but not including, 742ff6f02545212e991cd8b45011e40d2c2ef25a; c809195f5523dd4d09403bbb1c9732d548aa0d1e up to, but not including, abff41fd928328bbf3dda1140beb2e61fa424ccd; c809195f5523dd4d09403bbb1c9732d548aa0d1e up to, but not including, 03c574112e5d066df0ddce36d7438e850bcf3050; c809195f5523dd4d09403bbb1c9732d548aa0d1e up to, but not including, 1e2e2d9806944fe485824d617c8b7c78116c22db; c809195f5523dd4d09403bbb1c9732d548aa0d1e up to, but not including, cfb3ce07b705e486e022a2f2b1242b48f13981ff; c809195f5523dd4d09403bbb1c9732d548aa0d1e up to, but not including, 9591042533140dfe6608d9344806d567dcd39d02; c809195f5523dd4d09403bbb1c9732d548aa0d1e up to, but not including, 0f8690e3869109cd5803ccb400889d20a0b54e0e; c809195f5523dd4d09403bbb1c9732d548aa0d1e up to, but not including, 5521ae71e32a8069ed4ca6e792179dc57bc43ab2; and 3 more ranges742ff6f02545212e991cd8b45011e40d2c2ef25a, abff41fd928328bbf3dda1140beb2e61fa424ccd, 03c574112e5d066df0ddce36d7438e850bcf3050, 1e2e2d9806944fe485824d617c8b7c78116c22db, cfb3ce07b705e486e022a2f2b1242b48f13981ff, 9591042533140dfe6608d9344806d567dcd39d02

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
LocalThe attacker needs local access or must trick a user into running something.
Attack complexity
LowNo special conditions are needed; the attack works reliably.
Privileges required
LowA basic user account is enough.
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
HighData or code can be modified at will.
Availability
HighThe component can be taken down completely.

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

Official description

In the Linux kernel, the following vulnerability has been resolved: rds: drop incoming messages that cross network namespace boundaries rds_find_bound() looks up the destination socket using a global rhashtable keyed solely on (addr, port, scope_id). Network namespaces are not part of the key, so a sender in netns A can deliver an incoming message (inc) to a socket that lives in a different netns B. When this happens, inc->i_conn points to an rds_connection whose c_net is netns A, but the receiving rs lives in netns B. Once the child process that created netns A exits, cleanup_net() calls rds_loop_exit_net() -> rds_loop_kill_conns() -> rds_conn_destroy(), freeing that connection. If the survivor socket in netns B still holds the inc, any subsequent dereference of inc->i_conn is a use-after-free. There are two dangerous sites in rds_clear_recv_queue(): 1. inc->i_conn->c_lcong (offset 88 of freed rds_connection, size 200) read via rds_recv_rcvbuf_delta() -- confirmed by KASAN. 2. inc->i_conn->c_trans->inc_free(inc) (function pointer at offset 80) called via rds_inc_put() when the inc refcount reaches zero -- same race window, potential call-through-freed-object primitive. The bug is reachable from unprivileged user namespaces (CLONE_NEWUSER + CLONE_NEWNET), available since Linux 3.8. Fix this by rejecting the delivery in rds_recv_incoming() when the socket returned by rds_find_bound() belongs to a different network namespace than the connection that carried the message. Use the existing rds_conn_net() / sock_net() helpers and net_eq() for the comparison.

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

The underlying weakness: Use After Free

The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory belongs to the code that operates on the new pointer.

How developers prevent this class of flaw

  • Choose a language that provides automatic memory management.
  • When freeing pointers, be sure to set them to NULL once they are freed. However, the utilization of multiple or complex data structures may lower the usefulness of this strategy.

More Use After Free vulnerabilities (CWE-416)

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: total).
  3. Record last changed materially (score, affected products, status or references).

References

Recent Use After Free vulnerabilities

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