td has pre-auth denial of service via unbounded memory allocation in proto.UnencryptedMessage.Decode

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

7.5 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS

• CVE-2026-54638: 0.63% estimated exploitation activity in the next 30 days; percentile 50.23 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Impact A remote, unauthenticated attacker can cause excessive memory allocation (and resulting CPU / GC pressure, potentially OOM termination) by sending a crafted unencrypted MTProto packet. (proto.UnencryptedMessage).Decode read an attacker-controlled 32-bit dataLen field and immediately allocated a buffer of that size via make([]byte, dataLen) before validating that the underlying buffer actually contained that many bytes. A 20-byte packet declaring a ~1.75 GB payload (e.g. dataLen = 0x70000000) forces the runtime to provision and zero-initialize a multi-gigabyte heap allocation before the length is rejected. Unencrypted messages are part of the unauthenticated MTProto handshake path, so no credentials or established session are required to reach the vulnerable code. Impact is limited to availability; there is no evidence of memory corruption, out-of-bounds access, or code execution. Patches Fixed in v0.145.1 by validating dataLen against the remaining buffer length before…

Published by the source

28 Jul 2026, 22:15 UTC

Last modified by the source

18 Aug 2026, 17:15 UTC

Source last checked

26 Oct 2026, 15:27 UTC

1. Revision 3 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-whmm-qj9r-wvr2

2. Revision 2 · amended · 24 Oct 2026

   Amended from osv record GO-2026-6138

3. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-whmm-qj9r-wvr2

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# Patch Next advisory brief: CVE-2026-54638

Advisory: td has pre-auth denial of service via unbounded memory allocation in proto.UnencryptedMessage.Decode
IDs: CVE-2026-54638, GHSA-whmm-qj9r-wvr2
Record: https://patchnext.com/advisories/cve-2026-54638 (revision 3, source checked 26 Oct 2026, 15:27 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 7.5)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: github.com/gotd/td 0.145.1. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/gotd/td: affected < 0.145.1; fixed in 0.145.1

## Suggested inspection (read-only)
- Go github.com/gotd/td: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on github.com/gotd/td.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-whmm-qj9r-wvr2 (OSV record GHSA-whmm-qj9r-wvr2 lists affected ranges: Go github.com/gotd/td >=0 <0.145.1 (fixed))
- Verified: https://osv.dev/vulnerability/GO-2026-6138 (OSV record GO-2026-6138 lists affected ranges: Go github.com/gotd/td >=0 <0.145.1 (fixed))
- Verified: https://github.com/advisories/GHSA-whmm-qj9r-wvr2 (GitHub-reviewed advisory GHSA-whmm-qj9r-wvr2 lists affected ranges: Go github.com/gotd/td >=0 <0.145.1)

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