VulnerabilityPublished 25 Sep 2026Updated 19 Oct 2026

CVE-2026-97964: Linux kernel · ppp_synctty: ensure a writeable skb header

Affects Linux kernelSource CVE Database V5

Not known to be exploited · fixed in a256f9925288ef47de8febed5c38d5cc21340211 : update Linux kernel when convenient.

Data as of 26 Oct 2026, 12:55 UTC

Severity

Unrated

Rated by Threat Radar · CVSS not yet scored by NVD

EPSS: 0.1% chance of exploitation in 30 days – higher than 6% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in a256f9925288ef47de8febed5c38d5cc21340211, 7953946f68262a8bb137aa101249adef6e029652, 0996c3e6bcc6ae08cb371ed43648c9f7f748ae6e +4

Exploitation evidence

Disclosed: evidence found.
CVE published 25 Sep 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 to a fixed release listed under Affected software.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected ≥ 4cf476ced45d7f12df30a68e833b263e7a2202d1, < a256f9925288ef47de8febed5c38d5cc21340211	Fixed in a256f9925288ef47de8febed5c38d5cc21340211
LinuxLinux	Affected ≥ 4cf476ced45d7f12df30a68e833b263e7a2202d1, < 7953946f68262a8bb137aa101249adef6e029652	Fixed in 7953946f68262a8bb137aa101249adef6e029652
LinuxLinux	Affected ≥ 4cf476ced45d7f12df30a68e833b263e7a2202d1, < 0996c3e6bcc6ae08cb371ed43648c9f7f748ae6e	Fixed in 0996c3e6bcc6ae08cb371ed43648c9f7f748ae6e
LinuxLinux	Affected ≥ 4cf476ced45d7f12df30a68e833b263e7a2202d1, < 25e03eeead2c49748c7582dfb64c205f93a42d00	Fixed in 25e03eeead2c49748c7582dfb64c205f93a42d00
LinuxLinux	Affected ≥ 4cf476ced45d7f12df30a68e833b263e7a2202d1, < 15d0a6c9a42df2d745c37510dba828f6dbe60d9f	Fixed in 15d0a6c9a42df2d745c37510dba828f6dbe60d9f
LinuxLinux	Affected ≥ 4cf476ced45d7f12df30a68e833b263e7a2202d1, < 8aaeb56aff2a557a88f83ae866da2c91ad247e59	Fixed in 8aaeb56aff2a557a88f83ae866da2c91ad247e59

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.

References

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