CVE-2026-97964

ppp_synctty: ensure a writeable skb header

State: Published
Severity: Not scored
Published: Sep 25, 2026
Updated: Oct 19, 2026
Reserved: Sep 25, 2026

Description

In the Linux kernel, the following vulnerability has been resolved:

ppp_synctty: ensure a writeable skb header

ppp_sync_txmunge() checks headroom before prepending the address and control bytes, but does not ensure that the skb header is writable. A received skb can reach this function through PPP channel bridging without passing through ppp_start_xmit(), which calls skb_cow_head().

For example, a PPPoE frame may share its buffer with a clone queued to an AF_PACKET socket. If it is bridged to a synchronous tty channel, the address/control bytes can overwrite data still visible to that socket.

Use skb_cow_head() to ensure both sufficient headroom and a writable header.

Scores

The record has no CVSS score.

Weaknesses

The record names no weakness.

Affected Products

Product	Versions
LinuxLinux	4cf476ced45d7f12df30a68e833b263e7a2202d1 to before 25e03eeead2c49748c7582dfb64c205f93a42d00Affected 4cf476ced45d7f12df30a68e833b263e7a2202d1 to before a256f9925288ef47de8febed5c38d5cc21340211Affected 4cf476ced45d7f12df30a68e833b263e7a2202d1 to before 7953946f68262a8bb137aa101249adef6e029652Affected 4cf476ced45d7f12df30a68e833b263e7a2202d1 to before 3af7797fbabc84992e0ca5ad2bc0ca8537d053efAffected 4cf476ced45d7f12df30a68e833b263e7a2202d1 to before 0996c3e6bcc6ae08cb371ed43648c9f7f748ae6eAffected 4cf476ced45d7f12df30a68e833b263e7a2202d1 to before 15d0a6c9a42df2d745c37510dba828f6dbe60d9fAffected 4cf476ced45d7f12df30a68e833b263e7a2202d1 to before 8aaeb56aff2a557a88f83ae866da2c91ad247e59Affected
LinuxLinux	5.11Affected before 5.11Not affected 5.15.222 through 5.15.Not affected 6.1.189 through 6.1.Not affected 6.6.158 through 6.6.Not affected 6.12.111 through 6.12.Not affected 6.18.53 through 6.18.Not affected 7.2.7 through 7.2.Not affected 7.3 and laterNot affected

Product

Versions

LinuxLinux

4cf476ced45d7f12df30a68e833b263e7a2202d1 to before 25e03eeead2c49748c7582dfb64c205f93a42d00Affected
4cf476ced45d7f12df30a68e833b263e7a2202d1 to before a256f9925288ef47de8febed5c38d5cc21340211Affected
4cf476ced45d7f12df30a68e833b263e7a2202d1 to before 7953946f68262a8bb137aa101249adef6e029652Affected
4cf476ced45d7f12df30a68e833b263e7a2202d1 to before 3af7797fbabc84992e0ca5ad2bc0ca8537d053efAffected
4cf476ced45d7f12df30a68e833b263e7a2202d1 to before 0996c3e6bcc6ae08cb371ed43648c9f7f748ae6eAffected
4cf476ced45d7f12df30a68e833b263e7a2202d1 to before 15d0a6c9a42df2d745c37510dba828f6dbe60d9fAffected
4cf476ced45d7f12df30a68e833b263e7a2202d1 to before 8aaeb56aff2a557a88f83ae866da2c91ad247e59Affected

LinuxLinux

5.11Affected
before 5.11Not affected
5.15.222 through 5.15.*Not affected
6.1.189 through 6.1.*Not affected
6.6.158 through 6.6.*Not affected
6.12.111 through 6.12.*Not affected
6.18.53 through 6.18.*Not affected
7.2.7 through 7.2.*Not affected
7.3 and laterNot affected

References

Every record here comes from the CVE Program’s CVE List. © 1999–2026 The MITRE Corporation. CVE is a registered trademark of The MITRE Corporation. The records are reproduced under the CVE Program terms of use.