5.5

CVE-2022-49372: tcp: tcp_rtx_synack() can be called from process context

Analyzed
AliasesUBUNTU-CVE-2022-49372DEBIAN-CVE-2022-49372
Published 26-02-2025Last modified 11-05-2026

Vulnerability summary

CVE-2022-49372 is a medium (CVSS 5.5) vulnerability in linux. EPSS estimates a 0.29% chance of exploitation in the next 30 days, higher than 21.7% of scored vulnerabilities.

Priority
Routine

Not severe (CVSS 5.5, local access); no exploitation reported by the 5 checked sources

Source freshness unavailable

How is this decided?
CVSS score
5.5/10
010
Medium · v3.1 (NVD)
EPSS score
0.29%
0%100%
Low · 0.00 pp in 30 days
KEVNot listedNot listed by any tracked catalog.
RansomwareNot flaggedNo ransomware use recorded.
Public exploits0No public exploits recorded

Advisory lineage

Upstream 0 · Downstream 3 · Related 1
RHSA-2023:2458RHSA-2023:2951SUSE-SU-2025:1293-1

Timeline

  1. 26-02-2025
    PublishedVulnerability first disclosed.
  2. 11-05-2026
    Last modifiedVulnerability information updated.

Description

In the Linux kernel, the following vulnerability has been resolved: tcp: tcp_rtx_synack() can be called from process context Laurent reported the enclosed report [1] This bug triggers with following coditions: 0) Kernel built with CONFIG_DEBUG_PREEMPT=y 1) A new passive FastOpen TCP socket is created. This FO socket waits for an ACK coming from client to be a complete ESTABLISHED one. 2) A socket operation on this socket goes through lock_sock() release_sock() dance. 3) While the socket is owned by the user in step 2), a retransmit of the SYN is received and stored in socket backlog. 4) At release_sock() time, the socket backlog is processed while in process context. 5) A SYNACK packet is cooked in response of the SYN retransmit. 6) -> tcp_rtx_synack() is called in process context. Before blamed commit, tcp_rtx_synack() was always called from BH handler, from a timer handler. Fix this by using TCP_INC_STATS() & NET_INC_STATS() which do not assume caller is in non preemptible context. [1] BUG: using __this_cpu_add() in preemptible [00000000] code: epollpep/2180 caller is tcp_rtx_synack.part.0+0x36/0xc0 CPU: 10 PID: 2180 Comm: epollpep Tainted: G OE 5.16.0-0.bpo.4-amd64 #1 Debian 5.16.12-1~bpo11+1 Hardware name: Supermicro SYS-5039MC-H8TRF/X11SCD-F, BIOS 1.7 11/23/2021 Call Trace: <TASK> dump_stack_lvl+0x48/0x5e check_preemption_disabled+0xde/0xe0 tcp_rtx_synack.part.0+0x36/0xc0 tcp_rtx_synack+0x8d/0xa0 ? kmem_cache_alloc+0x2e0/0x3e0 ? apparmor_file_alloc_security+0x3b/0x1f0 inet_rtx_syn_ack+0x16/0x30 tcp_check_req+0x367/0x610 tcp_rcv_state_process+0x91/0xf60 ? get_nohz_timer_target+0x18/0x1a0 ? lock_timer_base+0x61/0x80 ? preempt_count_add+0x68/0xa0 tcp_v4_do_rcv+0xbd/0x270 __release_sock+0x6d/0xb0 release_sock+0x2b/0x90 sock_setsockopt+0x138/0x1140 ? __sys_getsockname+0x7e/0xc0 ? aa_sk_perm+0x3e/0x1a0 __sys_setsockopt+0x198/0x1e0 __x64_sys_setsockopt+0x21/0x30 do_syscall_64+0x38/0xc0 entry_SYSCALL_64_after_hwframe+0x44/0xae

CVSS metrics

4 scores · 3 sources · 2 versions

EPSS trend

Probability

0.29%

Chance of exploitation in the next 30 days

Percentile

22%

Versus all other CVEs

30-day change

No change 0.00 pp

From 0.29% on 04-10-2026

04-10-202603-11-2026

Known exploited

Compare KEV catalogs
CISA KEV

Not in the CISA KEV catalog.

ENISA CNW

Not in the ENISA CNW catalog.

CIRCL

Not in the CIRCL catalog.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

No weakness data has been published for this record.

Affected systems

Version check

Known conditions: local access, low-privilege account, no user interaction (CVSS vector). Other conditions: not stated in public data.

Ubuntu111 products
  • linuxAll versions (No fix recorded) | < 4.15.0-192.203 | < 5.4.0-126.142 | < 5.15.0-48.54
  • linux-allwinner-5.19All versions (No fix recorded)
  • linux-awsAll versions (No fix recorded) | < 4.15.0-1140.151 | < 5.4.0-1085.92 | < 5.15.0-1020.24
  • linux-aws-5.0All versions (No fix recorded)
  • linux-aws-5.11All versions (No fix recorded)
Linux2 products
  • linux≥ 168a8f58059a22feb9e9a2dcc1b8053dbbbc12ef, < 3db889f883e65bbd3b1401279bfc1e9ed255c481 | ≥ 168a8f58059a22feb9e9a2dcc1b8053dbbbc12ef, < c348b0f8d035fc4bdc040796889beec7218bd1b8 | ≥ 168a8f58059a22feb9e9a2dcc1b8053dbbbc12ef, < 58bd38cbc961fd799842b7be8c5222310f04b908 | ≥ 168a8f58059a22feb9e9a2dcc1b8053dbbbc12ef, < d05c2fdf8e10528bb6751bd95243e862d5402a9b | ≥ 168a8f58059a22feb9e9a2dcc1b8053dbbbc12ef, < 0a0f7f84148445c9f02f226928803a870139d820 | ≥ 168a8f58059a22feb9e9a2dcc1b8053dbbbc12ef, < 88cd232146207ff1d41dededed5e77c0d4438113 | ≥ 168a8f58059a22feb9e9a2dcc1b8053dbbbc12ef, < bdc28a8fb43cc476e33b11519235adb816ce00e8 | ≥ 168a8f58059a22feb9e9a2dcc1b8053dbbbc12ef, < d8e1bc6029acac796293310aacef7b7336f35b6a | ≥ 168a8f58059a22feb9e9a2dcc1b8053dbbbc12ef, < 0a375c822497ed6ad6b5da0792a12a6f1af10c0b | 3.7
  • linux_kernel≥ 3.7, < 4.9.318 | ≥ 4.10, < 4.14.283 | ≥ 4.15, < 4.19.247 | ≥ 4.20, < 5.4.198 | ≥ 5.5, < 5.10.122 | ≥ 5.11, < 5.15.47 | ≥ 5.16, < 5.17.15 | ≥ 5.18, < 5.18.4
Debian1 product
  • linux< 5.18.5-1

3 vendors · 114 products

References

13 links
Show all 13 references