Answer in brief
CVE-2026-68398 records a Unknown severity vulnerability in ppp: defer channel free to an RCU grace period to fix pppol2tp RX UAF. The current sources do not mark it as known exploited. The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
A CVSS score is not reported in the current record. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| Linux/Linuxgeneric | >=ee40fb2e1eb5bc0ddd3f2f83c6e39a454ef5a741 <4bb84e964ff0fe0a171c965362de72f9820dbce9 || >=ee40fb2e1eb5bc0ddd3f2f83c6e39a454ef5a741 <3ab32218d7182705dae5c86f13925f458072da2c || >=ee40fb2e1eb5bc0ddd3f2f83c6e39a454ef5a741 <c9574b8a8edeb4edd3ac6472c27ef7184bdb2baa || >=ee40fb2e1eb5bc0ddd3f2f83c6e39a454ef5a741 <06213c85d8c0994f786c093b8b2a517987943ca6 || >=ee40fb2e1eb5bc0ddd3f2f83c6e39a454ef5a741 <ec4215683e47424c9c4762fd3c60f552a3119142 || d36e5ba7bbed5d7bd26e8609ffed503c2def401b || 9bcc0508576b2d50efd958f2ea1c5906749c2c89 || c2984681fe15cfb803a9132aaaf1140ab20a72c1 || 5803ecd7f6ac6f747582e775caa62ac9d0489261 || 26f8819ddd10141ebe7bbce700fbab36bfa5f478 || >=3.2.99 <3.3 || >=3.16.54 <3.17 || >=4.4.225 <4.5 || >=4.9.225 <4.10 || >=4.14.182 <4.15 | 4bb84e964ff0fe0a171c965362de72f9820dbce9, 3ab32218d7182705dae5c86f13925f458072da2c, c9574b8a8edeb4edd3ac6472c27ef7184bdb2baa, 06213c85d8c0994f786c093b8b2a517987943ca6, ec4215683e47424c9c4762fd3c60f552a3119142, 3.3, 3.17, 4.5, 4.10, 4.15 |
| Linux/Linuxgeneric | 4.15 | Not reported |
Published upstream
Aug 10, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Aug 10, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Aug 10, 2026
In the Linux kernel, the following vulnerability has been resolved: ppp: defer channel free to an RCU grace period to fix pppol2tp RX UAF pppol2tp_recv() runs in the L2TP UDP-encap softirq RX path: l2tp_udp_encap_recv() -> l2tp_recv_common() -> pppol2tp_recv() -> ppp_input(&po->chan) It runs under rcu_read_lock() holding only an l2tp_session reference and takes NO reference on the internal PPP channel (struct channel, chan->ppp) that ppp_input() dereferences. The pppox socket is SOCK_RCU_FREE, so 'po' and the embedded ppp_channel are RCU-safe. But the internal struct channel is a separate allocation that ppp_release_channel() frees with a plain kfree(): close(data socket) -> pppol2tp_release() -> pppox_unbind_sock() -> ppp_unregister_channel() -> ppp_release_channel() -> kfree(pch) For a channel that is bound (PPPIOCGCHAN) but not attached to a ppp unit (no PPPIOCCONNECT, pch->ppp == NULL) and not bridged, teardown skips both ppp_disconnect_channel()'s synchronize_net() and ppp_unbridge_channels()'s synchronize_rcu(), so the kfree() has no grace period. rcu_read_lock() in pppol2tp_recv() does not protect against a plain kfree(), so an in-flight ppp_input() on one CPU can dereference the channel just freed by close() on another CPU. The bug is reachable by an unprivileged user. Defer the channel free to an RCU callback via call_rcu() so the grace period fences any in-flight ppp_input(). The disconnect and unbridge teardown paths already fence with synchronize_net()/synchronize_rcu(); call_rcu() does the same here without stalling the close() path.
Quoted source text, attributed separately from HOL analysis.
Answer in brief
CVE-2026-68398 records a Unknown severity vulnerability in ppp: defer channel free to an RCU grace period to fix pppol2tp RX UAF. The current sources do not mark it as known exploited. The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
A CVSS score is not reported in the current record. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| Linux/Linuxgeneric | >=ee40fb2e1eb5bc0ddd3f2f83c6e39a454ef5a741 <4bb84e964ff0fe0a171c965362de72f9820dbce9 || >=ee40fb2e1eb5bc0ddd3f2f83c6e39a454ef5a741 <3ab32218d7182705dae5c86f13925f458072da2c || >=ee40fb2e1eb5bc0ddd3f2f83c6e39a454ef5a741 <c9574b8a8edeb4edd3ac6472c27ef7184bdb2baa || >=ee40fb2e1eb5bc0ddd3f2f83c6e39a454ef5a741 <06213c85d8c0994f786c093b8b2a517987943ca6 || >=ee40fb2e1eb5bc0ddd3f2f83c6e39a454ef5a741 <ec4215683e47424c9c4762fd3c60f552a3119142 || d36e5ba7bbed5d7bd26e8609ffed503c2def401b || 9bcc0508576b2d50efd958f2ea1c5906749c2c89 || c2984681fe15cfb803a9132aaaf1140ab20a72c1 || 5803ecd7f6ac6f747582e775caa62ac9d0489261 || 26f8819ddd10141ebe7bbce700fbab36bfa5f478 || >=3.2.99 <3.3 || >=3.16.54 <3.17 || >=4.4.225 <4.5 || >=4.9.225 <4.10 || >=4.14.182 <4.15 | 4bb84e964ff0fe0a171c965362de72f9820dbce9, 3ab32218d7182705dae5c86f13925f458072da2c, c9574b8a8edeb4edd3ac6472c27ef7184bdb2baa, 06213c85d8c0994f786c093b8b2a517987943ca6, ec4215683e47424c9c4762fd3c60f552a3119142, 3.3, 3.17, 4.5, 4.10, 4.15 |
| Linux/Linuxgeneric | 4.15 | Not reported |
Published upstream
Aug 10, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Aug 10, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Aug 10, 2026
In the Linux kernel, the following vulnerability has been resolved: ppp: defer channel free to an RCU grace period to fix pppol2tp RX UAF pppol2tp_recv() runs in the L2TP UDP-encap softirq RX path: l2tp_udp_encap_recv() -> l2tp_recv_common() -> pppol2tp_recv() -> ppp_input(&po->chan) It runs under rcu_read_lock() holding only an l2tp_session reference and takes NO reference on the internal PPP channel (struct channel, chan->ppp) that ppp_input() dereferences. The pppox socket is SOCK_RCU_FREE, so 'po' and the embedded ppp_channel are RCU-safe. But the internal struct channel is a separate allocation that ppp_release_channel() frees with a plain kfree(): close(data socket) -> pppol2tp_release() -> pppox_unbind_sock() -> ppp_unregister_channel() -> ppp_release_channel() -> kfree(pch) For a channel that is bound (PPPIOCGCHAN) but not attached to a ppp unit (no PPPIOCCONNECT, pch->ppp == NULL) and not bridged, teardown skips both ppp_disconnect_channel()'s synchronize_net() and ppp_unbridge_channels()'s synchronize_rcu(), so the kfree() has no grace period. rcu_read_lock() in pppol2tp_recv() does not protect against a plain kfree(), so an in-flight ppp_input() on one CPU can dereference the channel just freed by close() on another CPU. The bug is reachable by an unprivileged user. Defer the channel free to an RCU callback via call_rcu() so the grace period fences any in-flight ppp_input(). The disconnect and unbridge teardown paths already fence with synchronize_net()/synchronize_rcu(); call_rcu() does the same here without stalling the close() path.
Quoted source text, attributed separately from HOL analysis.