ppp_synctty: ensure a writeable skb header
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.
- Products
- Kernel
- Affected versions
- Not specified
- Fixed versions
- 5.15.222, 6.1.189, 6.12.111, 6.18.53, 6.6.158, 7.2.7
- CVEs
- CVE-2026-97964
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 5 Nov 2026, 06:14 UTC · Revision 1
Source evidence
ppp_synctty: ensure a writeable skb header
core-osv · Original sourcePublished 25 Sept 2026, 10:23 UTC
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.
osv:CVE-2026-97964
Kernel
Fixed versions: 5.15.222, 6.1.189, 6.6.158, 6.12.111, 6.18.53, 7.2.7
Complete source record
{
"id": "c326fd72ffbaa5e8aa901fe3f689dd9dcadd784cee16982c857a2d877037d25b",
"url": "https://osv.dev/vulnerability/CVE-2026-97964",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "ppp_synctty: ensure a writeable skb header",
"summary": "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.",
"evidence": "osv:CVE-2026-97964",
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"evidence": "/affected/1/ranges"
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"severity": "unknown",
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"package": {
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],
"modified": "2026-10-28T02:30:43.011965967Z",
"provider": "osv",
"references": [
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"https://git.kernel.org/stable/c/15d0a6c9a42df2d745c37510dba828f6dbe60d9f",
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"https://git.kernel.org/stable/c/7953946f68262a8bb137aa101249adef6e029652",
"https://git.kernel.org/stable/c/8aaeb56aff2a557a88f83ae866da2c91ad247e59",
"https://git.kernel.org/stable/c/a256f9925288ef47de8febed5c38d5cc21340211",
"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/97xxx/CVE-2026-97964.json",
"https://nvd.nist.gov/vuln/detail/CVE-2026-97964",
"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
],
"provider_metadata": {
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"osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/97xxx/CVE-2026-97964.json"
}
},
"related_cves": [
{
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"evidence": "/id"
}
],
"security_relevant": true,
"severity_evidence": null
},
"source_id": "core-osv",
"document_id": 511021,
"published_at": "2026-09-25T10:23:07.35+00:00"
}