CVE-2025-37749: net: ppp: Add bound checking for skb data on ppp_sync_txmung

Severity: high (CVSS 7.1 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.4% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2025-05-01 · updated 2026-07-30
Weakness: CWE-125

Description

In the Linux kernel, the following vulnerability has been resolved: net: ppp: Add bound checking for skb data on ppp_sync_txmung Ensure we have enough data in linear buffer from skb before accessing initial bytes. This prevents potential out-of-bounds accesses when processing short packets. When ppp_sync_txmung receives an incoming package with an empty payload: (remote) gef➤ p *(struct pppoe_hdr *) (skb->head + skb->network_header) $18 = { type = 0x1, ver = 0x1, code = 0x0, sid = 0x2, length = 0x0, tag = 0xffff8880371cdb96 } from the skb struct (trimmed) tail = 0x16, end = 0x140, head = 0xffff88803346f400 "4", data = 0xffff88803346f416 ":\377", truesize = 0x380, len = 0x0, data_len = 0x0, mac_len = 0xe, hdr_len = 0x0, it is not safe to access data[2]. [pabeni@redhat.com: fixed subj typo]

Affected products

Debian Linux: 11.0
Linux kernel: from 2.6.13 before 5.4.293; from 5.5 before 5.10.237; from 5.11 before 5.15.181; from 5.16 before 6.1.135; from 6.2 before 6.6.88; from 6.7 before 6.12.24 — fixed in 5.10.237, 5.15.181, 5.4.293, 6.1.135, 6.12.24, 6.13.12

How to fix

Upgrade to a fixed version: Linux kernel 5.10.237, 5.15.181, 5.4.293, 6.1.135. Check the vendor advisory for mitigations.

References

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