pppoe: drop PFC frames
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Impact type
- —
- Confidentiality · integrity · availability
- None · None · High
- Fix status
- Partial Red Hat: 2 without a fix
Attack profile from CVSS 3.1 · CNA. Fix status from CNA and Red Hat.
Summary
In the Linux kernel, the following vulnerability has been resolved: pppoe: drop PFC frames RFC 2516 Section 7 states that Protocol Field Compression (PFC) is NOT RECOMMENDED for PPPoE. In practice, pppd does not support negotiating PFC for PPPoE sessions, and the current PPPoE driver assumes an uncompressed (2-byte) protocol field. However, the generic PPP layer function ppp_input() is not aware of the negotiation result, and still accepts PFC frames. If a peer with a broken implementation or an attacker sends a frame with a compressed (1-byte) protocol field, the subsequent PPP payload is shifted by one byte. This causes the network header to be 4-byte misaligned, which may trigger unaligned access exceptions on some architectures. To reduce the attack surface, drop PPPoE PFC frames. Introduce ppp_skb_is_compressed_proto() helper function to be used in both ppp_generic.c and pppoe.c to avoid open-coding.
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- Yes
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| Linux | Linux | 5.0 and later | 5.10.258, 5.15.209, 6.1.175, 6.6.141, 6.12.91, 6.18.33, 7.0.10, 7.1 | Patch available | CNA |
- Linux VendorLinux Affected 5.0 and later Fixed in 5.10.258, 5.15.209, 6.1.175, 6.6.141, 6.12.91, 6.18.33, 7.0.10, 7.1 Patch available CNA
CPE configurations NVD · 1
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | 5.0 to before 5.10.258; 5.11 to before 5.15.209; 5.16 to before 6.1.175; 6.2 to before 6.6.141; 6.7 to before 6.12.91; 6.13 to before 6.18.33; 6.19 to before 7.0.10 | Vulnerable | Linux |
- cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* Versions 5.0 to before 5.10.258; 5.11 to before 5.15.209; 5.16 to before 6.1.175; 6.2 to before 6.6.141; 6.7 to before 6.12.91; 6.13 to before 6.18.33; 6.19 to before 7.0.10 Vulnerable ·Linux
Remediation
- Fix · CNA Linux (Linux) Fixed in 5.10.258, 5.15.209, 6.1.175, 6.6.141, 6.12.91, 6.18.33, 7.0.10, 7.1
Vendor assessments
Red Hat
Red Hat rating: Moderate. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| Red Hat Enterprise Linux 10 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux 9 | Affected | No fix yet: Fix deferred |
Not affected: 3 products
- Red Hat Enterprise Linux 6
- Red Hat Enterprise Linux 7
- Red Hat Enterprise Linux 8
Timeline
- 2026-10-02 Threatist record created from CVE-2026-53003
- 2026-10-03 Alias added: GHSA-7g5v-54rw-hq9g
- 2026-10-16 CISA SSVC decision points changed
- 2026-10-16 Priority changed: LOW → MEDIUM
- 2026-10-19 Weakness changed · CISA ADP
References
Patch 8
- https://git.kernel.org/stable/c/cb3beef35ab5e0c1afca9fd7648c6ae499786377
- https://git.kernel.org/stable/c/ba758fdf1399f310b30098b6faa3fd043de47dd2
- https://git.kernel.org/stable/c/fcca1df05322bb04e344dd1178b54b76a08eb7c3
- https://git.kernel.org/stable/c/8a5e840babc5c0fbd10c73728a13192347771ec6
- https://git.kernel.org/stable/c/49e41b60ccd1bdbe9e218420f716dd5f9a2f9c71
- https://git.kernel.org/stable/c/0cab5d077dd1efd2bd1a47271acc35894f945b4f
- https://git.kernel.org/stable/c/2b5c3c040d020e3ab3b9a8887031202d96843b1e
- https://git.kernel.org/stable/c/cc1ff87bce1ccd38410ab10960f576dcd17db679
More Linux Kernel vulnerabilities
- TI-2025-26358 tls: fix handling of zero-length records on the rx_list KEVCVSS 3.1CRITICAL 9.8
- TI-2026-38352 netfilter: bridge: make ebt_snat ARP rewrite writable KEVCVSS 3.1HIGH 8.8
- TI-2013-05264 The (1) get_user and (2) put_user API functions in the Linux kernel before 3.5.5 on the… KEVCVSS 3.1HIGH 8.8
- TI-2022-00125 Integer overflow in kernel KEVCVSS 3.1HIGH 8.4
- TI-2013-01864 The perf_swevent_init function in kernel/events/core.c in the Linux kernel before 3.8.9… KEVCVSS 3.1HIGH 8.4
- TI-2021-05514 Heap Out-Of-Bounds Write in Netfilter IP6T_SO_SET_REPLACE KEVCVSS 3.1HIGH 8.3
Sources
- CVE-2026-53003 · CVE Program
- CVE-2026-53003 · NVD
- FIRST EPSS
- GHSA-7g5v-54rw-hq9g · GitHub Advisory Database · CC BY 4.0
- CVE-2026-53003 · Red Hat security data · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences