pppoatm: ensure a writable skb header and linear data
Summary
| CVE | CVE-2026-98287 |
|---|---|
| State | PUBLISHED |
| Assigner | Linux |
| Source Priority | CVE Program / NVD first with legacy fallback |
| Published | 2026-10-06 09:18:18 UTC |
| Updated | 2026-10-19 10:18:30 UTC |
| Description | In the Linux kernel, the following vulnerability has been resolved: pppoatm: ensure a writable skb header and linear data In pppoatm_send(), LLC encapsulation checks whether there is sufficient headroom for the 4-byte LLC header, but does not ensure that the skb header is writable. Normal transmit packets passing through ppp_start_xmit() have their header unshared via skb_cow_head(). However, packets can also reach pppoatm_send() via PPP channel bridging (PPPIOCBRIDGECHAN) without going through ppp_start_xmit(). Use skb_cow_head() to ensure both sufficient headroom and a writable header before pushing the LLC header. While at it: - Call pskb_may_pull(skb, 1) before inspecting skb->data[0] to prevent out-of-bounds reads on zero-length or non-linear frames (e.g. from bridging). - Defer SC_COMP_PROT protocol compression until after pppoatm_may_send() succeeds. This eliminates the temporary skb allocation on admission failure and completely removes the fragile "undo" heuristic at the nospace label, avoiding any risk of reading uninitialized headroom or performing an unbalanced skb_push(). |
Risk And Classification
EPSS: 0.001800000 probability, percentile 0.069200000 (date 2026-10-06)
Vendor Declared Affected Products
| Source | Vendor | Product | Version | Platforms |
|---|---|---|---|---|
| CNA | Linux | Linux | affected 4cf476ced45d7f12df30a68e833b263e7a2202d1 208ccc4d08b1897451e9ba01c016bf93ff107966 git | Not specified |
| CNA | Linux | Linux | affected 4cf476ced45d7f12df30a68e833b263e7a2202d1 e6cd1bba7d113c15c00ac63671213a096fe4d686 git | Not specified |
| CNA | Linux | Linux | affected 4cf476ced45d7f12df30a68e833b263e7a2202d1 ffc448eb54f5ba80d4212c1e870cdb92b0f709fa git | Not specified |
| CNA | Linux | Linux | affected 4cf476ced45d7f12df30a68e833b263e7a2202d1 8e66c5969acd859ba72fb0a7fa895623fc1b3769 git | Not specified |
| CNA | Linux | Linux | affected 4cf476ced45d7f12df30a68e833b263e7a2202d1 e2f5529b0016db7d34f411408607f5cf395a542e git | Not specified |
| CNA | Linux | Linux | affected 4cf476ced45d7f12df30a68e833b263e7a2202d1 30992fe39e65589ed8e000425e088fa74994b811 git | Not specified |
| CNA | Linux | Linux | affected 4cf476ced45d7f12df30a68e833b263e7a2202d1 ecc7253683a3c55caa868ce0ee530fcb0044bd3c git | Not specified |
| CNA | Linux | Linux | affected 5.11 | Not specified |
| CNA | Linux | Linux | unaffected 5.11 semver | Not specified |
| CNA | Linux | Linux | unaffected 5.15.222 5.15.* semver | Not specified |
| CNA | Linux | Linux | unaffected 6.1.189 6.1.* semver | Not specified |
| CNA | Linux | Linux | unaffected 6.6.158 6.6.* semver | Not specified |
| CNA | Linux | Linux | unaffected 6.12.112 6.12.* semver | Not specified |
| CNA | Linux | Linux | unaffected 6.18.54 6.18.* semver | Not specified |
| CNA | Linux | Linux | unaffected 7.2.8 7.2.* semver | Not specified |
| CNA | Linux | Linux | unaffected 7.3 * original_commit_for_fix | Not specified |
References
| Reference | Source | Link | Tags |
|---|---|---|---|
| git.kernel.org/stable/c/ecc7253683a3c55caa868ce0ee530fcb0044bd3c | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/30992fe39e65589ed8e000425e088fa74994b811 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/e2f5529b0016db7d34f411408607f5cf395a542e | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/ffc448eb54f5ba80d4212c1e870cdb92b0f709fa | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/e6cd1bba7d113c15c00ac63671213a096fe4d686 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/208ccc4d08b1897451e9ba01c016bf93ff107966 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/8e66c5969acd859ba72fb0a7fa895623fc1b3769 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| CVE Program record | CVE.ORG | www.cve.org | canonical |
| NVD vulnerability detail | NVD | nvd.nist.gov | canonical, analysis |
No vendor comments have been submitted for this CVE.
There are currently no legacy QID mappings associated with this CVE.